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Friday, October 17, 2025

Genetic history of Africa

From Wikipedia, the free encyclopedia

The genetic history of Africa summarizes the genetic makeup and population history of African populations in Africa, composed of the overall genetic history, including the regional genetic histories of North Africa, West Africa, East Africa, Central Africa, and Southern Africa, as well as the recent origin of modern humans in Africa. The Sahara served as a trans-regional passageway and place of dwelling for people in Africa during various humid phasesand periods throughout the history of Africa. It also served as a biological barrier that restricted geneflow between the northern and central parts of Africa since its desertification, contributing to the diverse and distinct population structures on the continent. Nonetheless, this did not stop contact between peoples north and south of the Sahara at various points, especially in prehistoric times when the climate conditions were warmer and wetter.

Overview

The peoples of Africa are characterized by regional genetic substructure and heterogeneity, depending on the respective ethno-linguistic identity, and, in part, explainable by the "multiregional evolution" of modern human lineages in various multiple regions of the African continent, as well as later admixture events, including back-migrations from Eurasia, of both highly differentiated West and East Eurasian components.

Africans' genetic ancestry is largely partitioned by geography and language family, with populations belonging to the same ethno-linguistic groupings showing high genetic homogeneity and coherence. Gene flow, consistent with both short- and long-range migration events followed by extensive admixture and bottleneck events, have influenced the regional genetic makeup and demographic structure of Africans. The historical Bantu expansion had lasting impacts on the modern demographic make up of Africa, resulting in a greater genetic and linguistic homogenization. Genetic, archeologic, and linguistic studies added extra insight into this movement: "Our results reveal a genetic continuum of Niger–Congo speaker populations across the continent and extend our current understanding of the routes, timing and extent of the Bantu migration."

Overall, different African populations display genetic diversity and substructure, but can be clustered in distinct but partially overlapping groupings:

Khoisan or 'South African hunter-gatherers' from Southern Africa represented by the Khoisan peoples; they are associated with the deepest divergence (c. 270,000 years ago) of human genetic diversity, forming a distinct cluster of their own. They subsequently diverged into a Northern and Southern subgroup, c. 30,000 years ago.
'Central African hunter-gatherers' or 'Rain forest hunter-gatherers' (Pygmies) of Central Africa, represented by the Biaka and Mbuti; associated with another deep divergence (c. 220,000 years ago). They subsequently diverged into an Eastern and Western subgroup, c. 20,000 years ago.
"Ancestral Eurasians" represent the ancestral population of modern Eurasians shortly before the Out-of-Africa expansion; they are inferred to have diverged from other African populations, most likely somewhere in Northeast Africa, c. 70,000 years ago.
The various Afroasiatic-speakers from Northern Africa and the Horn of Africa, are suggested to have diverged from other African groups c. 50,000 years ago, but currently insufficient data and geneflow from other groups complicate an accurate estimation of the divergence date. Afroasiatic-speaking populations also display variable amounts of West Asian (primarily Natufian-like, but also Neolithic Anatolian and Iranian) admixtures from Eurasian backflow movements, with the remainder being primarily from autochthonous African genetic clusters, associated with Nilotic-like ancestry. They also display affinity for the Paleolithic North African Taforalt specimens of the Iberomaurusian culture.
'Eastern African hunter-gatherers', represented by Hadza, Sandawe, Omotic-speakers, and the ancient Mota specimen; their phylogenetic relationship to other populations is not clear, but they display affinity to modern East and West African populations, and harbor Khoesan-like geneflow along a Northeast to Southwest cline, as well as later (West) Eurasian admixtures, but at lower amounts than among Afroasiatic-speakers.
"Ancient East Africans" or "Ancestral West/East Africans" associated with the common ancestor of modern Niger-Congo and Nilo-Saharan-speakers originated around 28,000 years ago, likely in the Nile Valley region. They subsequently diverged at c. 18,000 years ago into the ancestors of West and West-Central African Niger-Congo and Bantu-speakers, and into the East African Nilo-Saharan/Nilotic-speakers. They represent the dominant and most widespreaded ancestry component of modern Africa, and are associated with relative recent population expansions linked to agriculture and pastoralist lifestyles. Genetic data indicates affinity for older hunter-gatherer groups in East Africa, but their exact relationship remains unclear. There is evidence for limited geneflow (9–13%) from a human ghost lineage, referred to as 'West African foragers' with a deeper or equally deep divergence time than 'Khoisan hunter-gatherers', into modern West Africans.
Austronesian-speaking Malagasy people in Madagascar have received significant East/Southeast Asian admixture associated with the Austronesian expansion, with the remainder ancestry being primarily associated with West-Central and East African components. The estimated date of geneflow between these sources is c. 2,200 years ago.

Indigenous Africans

The term 'indigenous Africans' refers to the populations with primarily indigenous (non-Eurasian) ancestries, consisting of Niger–Congo speakers, Nilo-Saharan speakers, the divergent and diverse Khoisan grouping, as well as of several unclassified or isolated ethnolinguistic groupings (see unclassified languages of Africa). The origin of the Afroasiatic languages remains disputed, with some proposing a Middle Eastern origin, while others support an African origin with varying degrees of Eurasian and African components. The Austronesian languages originated in southern East Asia, and later expanded outgoing from the Philippines.

The Niger–Congo languages probably originated in or near the area where these languages were spoken prior to Bantu expansion (i.e. West Africa or Central Africa). Its expansion may have been associated with the expansion of agriculture, in the African Neolithic period, following the desiccation of the Sahara in c. 3500 BCE. Proto-Niger-Congo may have originated about 10,000 years before present in the "Green Sahara" of Africa (roughly the Sahel and southern Sahara), and that its dispersal can be correlated with the spread of the bow and arrow by migrating hunter-gatherers, which later developed agriculture.

Although the validity of the Nilo-Saharan family remains controversial, the region between Chad, Sudan, and the Central African Republic is seen as a likely candidate for its homeland prior to its dispersal around 10,000–8,000 BCE.

The Southern African hunter-gatherers (Khoisan) are suggested to represent the autochthonous hunter-gatherer population of southern Africa, prior to the expansion of Bantu-speakers from Western/Central Africa and East African pastoralists. Khoisan show evidence for Bantu-related admixture, ranging from nearly ~0% to up to ~87.1%.

Out-of-Africa event

The "recent African origin of modern humans" proposes a "single origin" of Homo sapiens within Africa. Recent genetic and archeologic data suggests that Homo sapiens-subgroups originated in multiple regions of Africa, not confined to a single sub-region of origin, with the last common ancestor of all modern humans expanding from a single region absorbing or replacing various deep lineages (described as archaic ghosts). The H. sapiens ancestral to proper Eurasians most likely left Northeastern Africa between 50,000 and 100,000 years ago. The "recent African origin" model proposes that all modern non-African populations descend from one or several waves of H. sapiens that left Africa 70,000–60,000 years ago.

According to Durvasula et al. (2020), there are indications that 2% to 19% (≃6.6 to 7.0%) of the DNA of West African populations may have come from an unknown archaic hominin which split from the ancestor of humans and Neanderthals between 360 kya to 1.02 mya. However, Durvasula et al. (2020) also suggests that at least part of this archaic admixture is also present in Eurasians/non-Africans, and that the admixture event or events range from 0 to 124 ka B.P, which includes the period before the Out-of-Africa migration and prior to the African/Eurasian split (thus affecting in part the common ancestors of both Africans and Eurasians/non-Africans).Chen et al. (2020) found that Africans have higher Neanderthal ancestry than previously thought. 2,504 African samples from all over Africa were analyzed and tested on Neanderthal ancestry. All African samples showed evidence for minor Neanderthal ancestry, but always at lower levels than observed in Eurasians.

Geneflow between Eurasian and African populations

Significant Eurasian admixture is found in Northern Africa, and among specific ethnic groups of the Horn of Africa, Northern Sudan, the Sahel region, as well as among the Malagasy people of Madagascar. Various genome studies found evidence for multiple prehistoric back-migrations from various Eurasian populations and subsequent admixture with native groups. West Eurasian-associated geneflow arrived to Northern Africa during the Paleolithic (30,000 to 15,000 years ago), followed by other pre-Neolithic and Neolithic migration events. Genetic data on the Taforalt samples "demonstrated that Northern Africa received significant amounts of gene-flow from Eurasia predating the Holocene and development of farming practices". Medieval geneflow events, such as the Arab expansion also left traces in various African populations. Pickrell et al. (2014) indicated that Western Eurasian ancestry eventually arrived through Northeast Africa (particularly the Horn of Africa) to Southeast Africa and Southern Africa.

Ramsay et al. (2018) also found evidence for significant Western Eurasian admixture in various parts of Africa, from both ancient and more recent migrations, being highest among populations from Northern Africa, and some groups of the Horn of Africa:

In addition to the intrinsic diversity within the continent due to population structure and isolation, migration of Eurasian populations into Africa has emerged as a critical contributor to the genetic diversity. These migrations involved the influx of different Eurasian populations at different times and to different parts of Africa. Comprehensive characterization of the details of these migrations through genetic studies on existing populations could help to explain the strong genetic differences between some geographically neighbouring populations.
This distinctive Eurasian admixture appears to have occurred over at least three time periods with ancient admixture in central west Africa (e.g., Yoruba from Nigeria) occurring between ~7.5 and 10.5 kya, older admixture in east Africa (e.g., Ethiopia) occurring between ~2.4 and 3.2 kya and more recent admixture between ~0.15 and 1.5 kya in some east African (e.g., Kenyan) populations.
Subsequent studies based on LD decay and haplotype sharing in an extensive set of African and Eurasian populations confirmed the presence of Eurasian signatures in west, east and southern Africans. In the west, in addition to Niger-Congo speakers from The Gambia and Mali, the Mossi from Burkina Faso showed the oldest Eurasian admixture event ~7 kya. In the east, these analyses inferred Eurasian admixture within the last 4000 years in Kenya.

There is no definitive agreement on when or where the original homeland of the Afroasiatic language family existed. Some have suggested that they were spread by people with largely West-Eurasian ancestry during the Neolithic Revolution, towards Northern Africa and the Horn of Africa, outgoing from the Middle East, specifically from the Levant. Others argue that the first speakers of Proto-Afroasiatic were based in Northeast Africa because that region includes the majority of the diversity of the Afroasiatic language family and has very diverse groups in close geographic proximity, which is sometimes considered a telltale sign for a linguistic geographic origin. A subset of the Proto-Afroasiatic population would have migrated to the Levant during the late Paleolithic, merging with local West-Eurasians and resulting in a population which would later give rise to Natufian culture, associated with the early development of agriculture and early Afroasiatic languages, or specifically pre-proto-Semitic. In addition, Y-haplogroup sub-lineage E-M215 (also known as "E1b1b) and its derivative E-M35 are quite common among Afroasiatic speakers, and southwestern Ethiopia is a plausible source of these haplogroups. Under this African model, the linguistic group and carriers of this lineage would have arisen and dispersed together from Northeast Africa in the Mesolithic, plausibly having already developed subsistence patterns of pastoralism and intensive plant usage and collection.

The Near-Eastern agriculturalist hypothesis does not account for the domestication of plants endemic to the Horn of Africa such as teff, ensete, and Niger seed, nor does it account for the lack of evidence of intrusive agricultural populations or for the growing of wheat, barley, or sorghum in that region prior to 3000 B.C. According to historian and linguist Christopher Ehret, the form of intensive plant collection practiced by the Proto-Afroasiatic population in Northeast Africa may have been a precursor to the other agricultural practices that would later independently develop in the Fertile Crescent and the Horn of Africa.

Horn of Africa

While many studies conducted on Horn of Africa populations estimate a West-Eurasian admixture event around 3,000 years ago, Hodgson et al. (2014) found a distinct West-Eurasian ancestral component among studied Afroasiatic-speaking groups in the Horn of Africa (and to a lesser extent in North Africa and West Asia), most prevalent among the ethnic Somali. This ancestral component dubbed "Ethio-Somali" is most closely related to the "Maghrebi" (peaking in Tunisians) component and is believed to have diverged from other non-African ancestries around 23,000 years ago, and migrated back to Africa prior to developing agriculture (12–23 ka) from the Near East. This population would have crossed via the Sinai Peninsula and then split into two, with one branch continuing west across North Africa and the other heading south into the Horn of Africa. The authors propose that the "Ethio-Somali" component may have been a substantial ancestral component of the Proto-Afroasiatic-speaking population. Later migration from Arabia into the HOA beginning around 3 ka would explain the origin of the Ethiosemitic languages at this time. An mtDNA analysis by Gandini et al. (2016) has produced additional evidence in support of a pre-agricultural back-migration from West-Eurasia into the Horn of Africa with an estimated date of arrival into the Horn of Africa in the early Holocene, possibly as a result of obsidian exchange networks across the Red Sea. Hodgson et al. also confirmed the existence of an ancestral component indigenous to the Horn of Africa - "Ethiopic" or "Omotic" (Pagani et al.) - which is most prevalent among speakers of the Omotic branch of Afroasiatic in southwestern Ethiopia. This lineage is associated with that of a 4,500 year-old fossil (Mota) found in a cave in southwestern Ethiopia, which has high genetic affinity to modern Ethiopian groups, especially the endogamous blacksmith caste of the Omotic Aari people. Like Mota, Aari blacksmiths do not show evidence for admixture with West-Eurasians, demonstrating a degree of population continuity in this region for at least 4,500 years. In a comparative analysis of Mota's genome referencing modern populations, Gallego et al. (2016) concluded that the divergence of Omotic from other Afroasiatic languages may have resulted from the relative isolation of its speakers from external groups.

In an analysis of 68 Ethiopian ethnic groups, Lopez et al. (2021) revealed that several groups belonging to the three AA classifications of Cushitic, Omotic and Semitic show high genetic similarity to each other on average. Furthermore, the Nilo-Saharan speakers in the southwest shared more recent ancestry with Bantu and Nilotics, in contrast Afro-Asiatic speakers in the northeast shared more recent ancestry with Egyptians and other West Eurasians. The data also supported widespread recent intermixing among various ethnic groups.

Madagascar

Specific East Asian-related ancestry is found among the Malagasy speakers of Madagascar at a medium frequency. The presence of this East Asian-related ancestry is mostly linked to the Austronesian peoples expansion from Southeast Asia. The peoples of Borneo were identified to resemble the East Asian voyagers, who arrived on Madagascar. East Asian ancestry among Malagasy people was estimated at a mean average of 33%, but as high as ~75% among some Highlander groups and upper caste groups.

Northern Africa

Dobon et al. (2015) identified an autosomal ancestral component that is commonly found among modern Afroasiatic-speaking populations (as well as Nubians) in Northeast Africa. This Coptic component peaks among Copts in Sudan, which is differentiated by its lack of Arab influence, but shares common ancestry with the North African/Middle Eastern populations. It appears alongside a component that defines Nilo-Saharan speakers of southwestern Sudan and South Sudan. Arauna et al. (2017), analyzing existing genetic data obtained from Northern African populations, such as Berbers, described them as a mosaic of North African (Taforalt), Middle Eastern, European (Early European Farmers), and Sub-Saharan African-related ancestries.

Chen et al. (2020) analyzed 2,504 African samples from all over Africa, and found archaic Neanderthal ancestry, among all tested African samples at low frequency. They also identified a European-related (West-Eurasian) ancestry segment, which seems to largely correspond with the detected Neanderthal ancestry components. European-related admixture among Africans was estimated to be between ~0% to up to ~30%, with a peak among Northern Africans. According to Chen et al. (2020), "These data are consistent with the hypothesis that back-migration contributed to the signal of Neanderthal ancestry in Africans. Furthermore, the data indicates that this back-migration came after the split of Europeans and East Asians, from a population related to the European lineage."

There is a minor geneflow from North Africa in parts of Southern Europe, this is supported by the presence of an African-specific mitochondrial haplogroup among one of four 4,000 year old samples. Multiple studies found also evidence for geneflow of African ancestry towards Eurasia, specifically Europe and the Middle East. The analysis of 40 different West-Eurasian populations found African admixture at a frequency of 0% to up to ~15%.

Western Africa

Hollfelder et al. (2021) concluded that West African Yoruba people, which were previously used as "unadmixed reference population" for indigenous Africans, harbor minor levels of Neanderthal ancestry, which can be largely associated with back-migration of an "Ancestral European-like" source population.

A genome-wide study of a Fulani community from Burkina Faso inferred two major admixture events in this group, dating to ~1800 ya, and 300 ya. The first admixture event took place between the West African ancestors of the Fula and ancestral North African nomadic groups. The second admixture event, relatively recent, inferred a source from Southwestern Europe, or suggests either an additional gene flow between the Fulani and Northern African groups, who carry admixture proportions from Europeans. Sahelian populations like the Toubou also showed admixture coming from Eurasians.

Southern Africa

Low levels of West Eurasian ancestry (European or Middle Eastern) are found in Khoe–Kwadi Khoesan-speakers. It could have been acquired indirectly by admixture with migrating pastoralists from East Africa. This hypothesis of gene flow from eastern to southern Africa is further supported by other genetic and archaeological data documenting the spread of pastoralism from East to South Africa.

Regional genomic overview

North Africa

Archaic Human DNA

While Denisovan and Neanderthal ancestry in non-Africans outside of Africa are more certain, archaic human ancestry in Africans is less certain and is too early to be established with certainty.

Ancient DNA

Daniel Shriner (2018), using modern populations as a reference, showed that the Natufians carried 61.2% Arabian, 21.2% Northern African, 10.9% Western Asian, and a small portion of Eastern African ancestry at 6.8%, which is associated with the modern Omotic-speaking groups found in southern Ethiopia.

Egypt

Khnum-aa, Khnum-Nakht, Nakht-Ankh and JK2911 carried maternal haplogroup M1a1.

Djehutynakht (10A) carried maternal haplogroup U5b2b5. JK2888 carried maternal haplogroup U6a2.

Thuya, Tiye, Tutankhamen's mother, and Tutankhamen carried the maternal haplogroup K.

JK2134 carried maternal haplogroup J1d and JK2887 carried maternal haplogroup J2a1a1.

Amenhotep III, Akhenaten, and Tutankhamen carried the paternal haplogroup R1b.

Ramesses III and "Unknown Man E", possibly Pentawere, carried paternal haplogroup E1b1a.

JK2134 and JK2911 carried paternal haplogroup J.

Takabuti carried maternal haplogroup H4a1 and YM:KMM A 63 carried maternal haplogroup HV.

OM:KMM A 64 carried maternal haplogroup T2c1a.

JK2888 carried paternal haplogroup E1b1b1a1b2.

Libya

At Takarkori rockshelter, in Libya, two naturally mummified women, dated to the Middle Pastoral Period (7000 BP), carried basal maternal haplogroup N.

Morocco

Van de Loorsdrecht et al. (2018) found that of seven samples of Taforalts of Morocco, radiocarbon dated to between 15,100 cal BP and 13,900 cal BP, six were found to carry maternal haplogroup U6a, and one was found to carry maternal haplogroup M1b. All six males were found to carry paternal haplogroup E1b1b, and they harbored 63.5% Natufian-related ancestry and 36.5% Sub-Saharan African-related ancestry. The Sub-Saharan component is most strongly drawn out by modern West African groups such as the Yoruba and the Mende. The samples also contain an additional affinity to South, Central, and East African outgroups that cannot be explained by any known ancient or modern populations. When projected onto a principal component analysis graph of African and west Eurasian populations, the Taforalt individuals form a distinct cluster in an intermediate position between modern North Africans (e.g., Berbers, Mozabites, Saharawis) and East Africans (e.g., Afars, Oromos, Somalis). Jeong (2020), when comparing the Taforalt people of the Iberomaurusian culture to modern populations, found that the Taforalt's Sub-Saharan African genetic component may be best represented by modern West Africans (e.g., Yoruba).

Y-Chromosomal DNA

Mitochondrial DNA

Amid the Holocene, including the Holocene Climate Optimum in 8000 BP, Africans bearing haplogroup L2 spread within West Africa and Africans bearing haplogroup L3 spread within East Africa. As the largest migration since the Out of Africa migration, migration from Sub-Saharan Africa toward the North Africa occurred, by West Africans, Central Africans, and East Africans, resulting in migrations into Europe and Asia; consequently, Sub-Saharan African mitochondrial DNA was introduced into Europe and Asia. During the early period of the Holocene, 50% of Sub-Saharan African mitochondrial DNA was introduced into North Africa by West Africans and the other 50% was introduced by East Africans. During the modern period, a greater number of West Africans introduced Sub-Saharan African mitochondrial DNA into North Africa than East Africans.

Mitochondrial haplogroups L3, M, and N are found among Sudanese peoples (e.g., Beja, Nilotics, Nuba, Nubians), who have no known interaction (e.g., history of migration/admixture) with Europeans or Asians; rather than having developed in a post-Out-of-Africa migration context, mitochondrial macrohaplogroup L3/M/N and its subsequent development into distinct mitochondrial haplogroups (e.g., Haplogroup L3, Haplogroup M, Haplogroup N) may have occurred in East Africa at a time that considerably predates the Out-of-Africa migration event of 50,000 BP.

Autosomal DNA

Medical DNA

Lactase persistence

Neolithic agriculturalists, who may have resided in Northeast Africa and the Near East, may have been the source population for lactase persistence variants, including –13910*T, and may have been subsequently supplanted by later migrations of peoples. The Sub-Saharan West African Fulani, the North African Tuareg, and European agriculturalists, who are descendants of these Neolithic agriculturalists, share the lactase persistence variant –13910*T. While shared by Fulani and Tuareg herders, compared to the Tuareg variant, the Fulani variant of –13910*T has undergone a longer period of haplotype differentiation. The Fulani lactase persistence variant –13910*T may have spread, along with cattle pastoralism, between 9686 BP and 7534 BP, possibly around 8500 BP; corroborating this timeframe for the Fulani, by at least 7500 BP, there is evidence of herders engaging in the act of milking in the Central Sahara.

West Africa

Archaic Human DNA

Archaic traits found in human fossils of West Africa (e.g., Iho Eleru fossils, which dates to 13,000 BP) and Central Africa (e.g., Ishango fossils, which dates between 25,000 BP and 20,000 BP) may have developed as a result of admixture between archaic humans and modern humans or may be evidence of late-persisting early modern humans. While Denisovan and Neanderthal ancestry in non-Africans outside of Africa are more certain, archaic human ancestry in Africans is less certain and is too early to be established with certainty.

Ancient DNA

As of 2017, human ancient DNA has not been found in the region of West Africa. As of 2020, human ancient DNA has not been forthcoming in the region of West Africa.

Y-Chromosomal DNA

Eight male individuals from Guinea Bissau, two male individuals from Niger, one male individual from Mali, and one male individual from Cabo Verde carried haplogroup A1a.

As a result of haplogroup D0, a basal branch of haplogroup DE, being found in three Nigerian men, it may be the case that haplogroup DE, as well as its sublineages D0 and E, originated in Africa.

As of 19,000 years ago, Africans, bearing haplogroup E1b1a-V38, likely traversed across the Sahara, from east to west. E1b1a1-M2 likely originated in West Africa or Central Africa.

Mitochondrial DNA

Around 18,000 BP, Mende people, along with Gambian peoples, grew in population size.

In 15,000 BP, Niger-Congo speakers may have migrated from the Sahelian region of West Africa, along the Senegal River, and introduced L2a1 into North Africa, resulting in modern Mauritanian peoples and Berbers of Tunisia inheriting it.

Between 11,000 BP and 10,000 BP, Yoruba people and Esan people grew in population size.

As early as 11,000 years ago, Sub-Saharan West Africans, bearing macrohaplogroup L (e.g., L1b1a11, L1b1a6a, L1b1a8, L1b1a9a1, L2a1k, L3d1b1a), may have migrated through North Africa and into Europe, mostly into southern Europe (e.g., Iberia).

Autosomal DNA

During the early period of the Holocene, in 9000 BP, Khoisan-related peoples admixed with the ancestors of the Igbo people, possibly in the western Sahara.

Between 2000 BP and 1500 BP, Nilo-Saharan-speakers may have migrated across the Sahel, from East Africa into West Africa, and admixed with Niger-Congo-speaking Berom people. In 710 CE, West African-related populations (e.g., Niger-Congo-speaking Berom people, Bantu-speakers) and East African-related populations (Nilo-Saharan-speaking Ethiopians, Nilo-Saharan-speaking Chadians) admixed with one another in northern Nigeria and northern Cameroon.

Fan et al. (2019) found that the Fulani people show genetic affinity to isolated Afroasiatic-speaking groups in Eastern Africa, specifically Omotic-speakers such as the Aari people. While the Fulani have nearly exclusive indigenous African ancestry (defined by West and East African ancestry), they also show traces of West-Eurasian-like admixture, supporting an ancestral homeland somewhere in North or Eastern Africa, and westwards expansion during the Neolithic, possibly caused by the arrival and expansion of West-Eurasian-related groups. Fan et al. (2023) found that the Fulani, who have 50% Amhara-related and 50% Tikari-related ancestry as well as occupy regions such as West Africa, Central Africa, and the Sudan as nomadic herders, may have initially been Afroasiatic speakers that subsequently underwent language replacement and became Niger-Congo speakers.

Medical DNA

Pediculus

During the Copper Age and early Islamic era of ancient Israel, West Africans may have migrated into ancient Israel and introduced head louse from West Africa.

Sickle Cell

Amid the Green Sahara, the mutation for sickle cell originated in the Sahara or in the northwest forest region of western Central Africa (e.g., Cameroon) by at least 7,300 years ago, though possibly as early as 22,000 years ago. The ancestral sickle cell haplotype to modern haplotypes (e.g., Cameroon/Central African Republic and Benin/Senegal haplotypes) may have first arose in the ancestors of modern West Africans, bearing haplogroups E1b1a1-L485 and E1b1a1-U175 or their ancestral haplogroup E1b1a1-M4732. West Africans (e.g., Yoruba and Esan of Nigeria), bearing the Benin sickle cell haplotype, may have migrated through the northeastern region of Africa into the western region of Arabia. West Africans (e.g., Mende of Sierra Leone), bearing the Senegal sickle cell haplotype, may have migrated into Mauritania (77% modern rate of occurrence) and Senegal (100%); they may also have migrated across the Sahara, into North Africa, and from North Africa, into Southern Europe, Turkey, and a region near northern Iraq and southern Turkey. Some may have migrated into and introduced the Senegal and Benin sickle cell haplotypes into Basra, Iraq, where both occur equally. West Africans, bearing the Benin sickle cell haplotype, may have migrated into the northern region of Iraq (69.5%), Jordan (80%), Lebanon (73%), Oman (52.1%), and Egypt (80.8%).

Schistosomes

According to Steverding (2020), while not definite: Near the African Great Lakes, schistosomes (e.g., S. mansoni, S. haematobium) underwent evolution. Subsequently, there was an expansion alongside the Nile. From Egypt, the presence of schistosomes may have expanded, via migratory Yoruba people, into Western Africa. Thereafter, schistosomes may have expanded, via migratory Bantu peoples, into the rest of Sub-Saharan Africa (e.g., Southern Africa, Central Africa).

Thalassemia

Through pathways taken by caravans, or via travel amid the Almovarid period, a population (e.g., Sub-Saharan West Africans) may have introduced the –29 (A → G) β-thalassemia mutation (found in notable amounts among African Americans) into the North African region of Morocco.

Domesticated Animal DNA

While the Niger-Congo migration may have been from West Africa into Kordofan, possibly from Kordofan, Sudan, Niger-Congo speakers accompanied by undomesticated helmeted guineafowls, may have traversed into West Africa, domesticated the helmeted guineafowls by 3000 BCE, and via the Bantu expansion, traversed into other parts of Sub-Saharan Africa (e.g., Central Africa, East Africa, Southern Africa).

Central Africa

Archaic Human DNA

Ancient DNA

In 4000 BP, there may have been a population that traversed from Africa (e.g., West Africa or West-Central Africa), through the Strait of Gibraltar, into the Iberian Peninsula, where admixing between Africans and Iberians (e.g., of northern Portugal, of southern Spain) occurred.

Cameroon

West African hunter-gatherers, in the region of western Central Africa (e.g., Shum Laka, Cameroon), particularly between 8000 BP and 3000 BP, were found to be related to modern Central African hunter-gatherers (e.g., Baka, Bakola, Biaka, Bedzan).

Democratic Republic of Congo

At Kindoki, in the Democratic Republic of Congo, there were three individuals, dated to the protohistoric period (230 BP, 150 BP, 230 BP); one carried haplogroups E1b1a1a1d1a2 (E-CTS99, E-CTS99) and L1c3a1b, another carried haplogroup E (E-M96, E-PF1620), and the last carried haplogroups R1b1 (R-P25 1, R-M415) and L0a1b1a1.

Y-Chromosomal DNA

Haplogroup R1b-V88 is thought to have originated in Europe and migrated into Africa with farmers or herders in the Neolithic period, c. 5500 BC. R1b-V88 is found at a high frequency among Chadic speaking peoples such as the Hausa, as well as in Kanembu, Fulani, and Toubou populations.

Mitochondrial DNA

In 150,000 BP, Africans (e.g., Central Africans, East Africans) bearing haplogroup L1 diverged. Between 75,000 BP and 60,000 BP, Africans bearing haplogroup L3 emerged in East Africa and eventually migrated into and became present in modern West Africans, Central Africans, and non-Africans. Amid the Holocene, including the Holocene Climate Optimum in 8000 BP, Africans bearing haplogroup L2 spread within West Africa and Africans bearing haplogroup L3 spread within East Africa. As the largest migration since the Out of Africa migration, migration from Sub-Saharan Africa toward the North Africa occurred, by West Africans, Central Africans, and East Africans, resulting in migrations into Europe and Asia; consequently, Sub-Saharan African mitochondrial DNA was introduced into Europe and Asia.

Mitochondrial haplogroup L1c is strongly associated with pygmies, especially with Bambenga groups. L1c prevalence was variously reported as: 100% in Ba-Kola, 97% in Aka (Ba-Benzélé), and 77% in Biaka, 100% of the Bedzan (Tikar), 97% and 100% in the Baka people of Gabon and Cameroon, respectively, 97% in Bakoya (97%), and 82% in Ba-Bongo. Mitochondrial haplogroups L2a and L0a are prevalent among the Bambuti.

Autosomal DNA

Genetically, African pygmies have some key difference between them and Bantu peoples.

Medical DNA

Evidence suggests that, when compared to other Sub-Saharan African populations, African pygmy populations display unusually low levels of expression of the genes encoding for human growth hormone and its receptor associated with low serum levels of insulin-like growth factor-1 and short stature.

The genomes of Africans commonly found to undergo adaptation are regulatory DNA, and many cases of adaptation found among Africans relate to diet, physiology, and evolutionary pressures from pathogens. Throughout Sub-Saharan Africa, genetic adaptation (e.g., rs334 mutation, Duffy blood group, increased rates of G6PD deficiency, sickle cell disease) to malaria has been found among Sub-Saharan Africans, which may have initially developed in 7300 BP. Sub-Saharan Africans have more than 90% of the Duffy-null genotype. In the rainforests of Central Africa, genetic adaptation for non-height-related factors (e.g., immune traits, reproduction, thyroid function) and short stature (e.g., EHB1 and PRDM5 – bone synthesis; OBSCN and COX10 – muscular development; HESX1 and ASB14 – pituitary gland's growth hormone production/secretion) has been found among rainforest hunter-gatherers.

Eastern Africa

From the region of Kenya and Tanzania to South Africa, eastern Bantu-speaking Africans constitute a north to south genetic cline; additionally, from eastern Africa to toward southern Africa, evidence of genetic homogeneity is indicative of a serial founder effect and admixture events having occurred between Bantu-speaking Africans and other African populations by the time the Bantu migration had spanned into South Africa.

Archaic Human DNA

While Denisovan and Neanderthal ancestry in non-Africans outside of Africa are more certain, archaic human ancestry in Africans is less certain and is too early to be established with certainty.

Ancient DNA

Ethiopia

At Mota, in Ethiopia, an individual, estimated to date to the 5th millennium BP, carried haplogroups E1b1 and L3x2a. The individual of Mota is genetically related to groups residing near the region of Mota, and in particular, are considerably genetically related to the Aari people, especially the blacksmith caste of that group.

Kenya

At Jawuoyo Rockshelter, in Kisumu County, Kenya, a forager of the Later Stone Age carried haplogroups E1b1b1a1b2/E-V22 and L4b2a2c.

At Ol Kalou, in Nyandarua County, Kenya, a pastoralist of the Pastoral Neolithic carried haplogroups E1b1b1b2b2a1/E-M293 and L3d1d.

At Kokurmatakore, in Marsabit County, Kenya, a pastoralist of the Pastoral Iron Age carried haplogroups E1b1b1/E-M35 and L3a2a.

At White Rock Point, in Homa Bay County, Kenya, there were two foragers of the Later Stone Age; one carried haplogroups BT (xCT), likely B, and L2a4, and another probably carried haplogroup L0a2.

At Nyarindi Rockshelter, in Kenya, there were two individuals, dated to the Later Stone Age (3500 BP); one carried haplogroup L4b2a and another carried haplogroup E (E-M96, E-P162).

At Lukenya Hill, in Kenya, there were two individuals, dated to the Pastoral Neolithic (3500 BP); one carried haplogroups E1b1b1b2b (E-M293, E-CTS10880) and L4b2a2b, and another carried haplogroup L0f1.

At Hyrax Hill, in Kenya, an individual, dated to the Pastoral Neolithic (2300 BP), carried haplogroups E1b1b1b2b (E-M293, E-M293) and L5a1b.

At Molo Cave, in Kenya, there were two individuals, dated to the Pastoral Neolithic (1500 BP); while one had haplogroups that went undetermined, another carried haplogroups E1b1b1b2b (E-M293, E-M293) and L3h1a2a1.

At Kakapel, in Kenya, there were three individuals, one dated to the Later Stone Age (3900 BP) and two dated to the Later Iron Age (300 BP, 900 BP); one carried haplogroups CT (CT-M168, CT-M5695) and L3i1, another carried haplogroup L2a1f, and the last carried haplogroup L2a5.

At Panga ya Saidi, in Kenya, an individual, estimated to date between 496 BP and 322 BP, carried haplogroups E1b1b1b2 and L4b2a2.

At Kilifi, Mtwapa, in Kenya, an individual, dated between 1250 CE and 1650 CE, carried haplogroup L3b1a1a.

Tanzania

At Mlambalasi rockshelter, in Tanzania, an individual, dated between 20,345 BP and 17,025 BP, carried undetermined haplogroups.

At Gishimangeda Cave, in Karatu District, Tanzania, there were eleven pastoralists of the Pastoral Neolithic; one carried haplogroups E1b1b1a1b2/E-V22 and HV1b1, another carried haplogroup L0a, another carried haplogroup L3x1, another carried haplogroup L4b2a2b, another carried haplogroups E1b1b1b2b2a1/E-M293 and L3i2, another carried haplogroup L3h1a2a1, another carried haplogroups E1b1b1b2b2/E-V1486, likely E-M293 and L0f2a1, and another carried haplogroups E1b1b1b2b2/E-V1486, likely E-M293, and T2+150; while most of the haplogroups among three pastoralists went undetermined, one was determined to carry haplogroup BT, likely B.

At Kilwa, Coast, in Tanzania, an individual, dated between 1300 CE and 1600 CE, carried haplogroups J2a2a1a1a2a~ and L2a1h.

At Lindi, in Tanzania, an individual, dated between 1511 cal CE and 1664 cal CE, carried haplogroups E1b1a1a1a2a1a3a1d~ and L0a1a2.

At Makangale Cave, on Pemba Island, Tanzania, an individual, estimated to date between 1421 BP and 1307 BP, carried haplogroup L0a.

At Songo Mnara, in Tanzania, an individual, dated between 1294 cal CE and 1392 cal CE, carried haplogroups R1a and L3e3a.

Uganda

At Munsa, in Uganda, an individual, dated to the Later Iron Age (500 BP), carried haplogroup L3b1a1.

Y-Chromosomal DNA

As of 19,000 years ago, Africans, bearing haplogroup E1b1a-V38, likely traversed across the Sahara, from east to west.

Before the slave trade period, East Africans, who carried haplogroup E1b1a-M2, expanded into Arabia, resulting in various rates of inheritance throughout Arabia (e.g., 2.8% Qatar, 3.2% Yemen, 5.5% United Arab Emirates, 7.4% Oman).

Mitochondrial DNA

In 150,000 BP, Africans (e.g., Central Africans, East Africans) bearing haplogroup L1 diverged. In 130,000 BP, Africans bearing haplogroup L5 diverged in East Africa. Between 130,000 BP and 75,000 BP, behavioral modernity emerged among Southern Africans and long-term interactions between the regions of Southern Africa and Eastern Africa became established. Between 75,000 BP and 60,000 BP, Africans bearing haplogroup L3 emerged in East Africa and eventually migrated into and became present in modern West Africans, Central Africans, and non-Africans. Amid the Holocene, including the Holocene Climate Optimum in 8000 BP, Africans bearing haplogroup L2 spread within West Africa and Africans bearing haplogroup L3 spread within East Africa. As the largest migration since the Out of Africa migration, migration from Sub-Saharan Africa toward the North Africa occurred, by West Africans, Central Africans, and East Africans, resulting in migrations into Europe and Asia; consequently, Sub-Saharan African mitochondrial DNA was introduced into Europe and Asia. During the early period of the Holocene, 50% of Sub-Saharan African mitochondrial DNA was introduced into North Africa by West Africans and the other 50% was introduced by East Africans. During the modern period, a greater number of West Africans introduced Sub-Saharan African mitochondrial DNA into North Africa than East Africans. Between 15,000 BP and 7000 BP, 86% of Sub-Saharan African mitochondrial DNA was introduced into Southwest Asia by East Africans, largely in the region of Arabia, which constitute 50% of Sub-Saharan African mitochondrial DNA in modern Southwest Asia. In the modern period, 68% of Sub-Saharan African mitochondrial DNA was introduced by East Africans and 22% was introduced by West Africans, which constitutes 50% of Sub-Saharan African mitochondrial DNA in modern Southwest Asia.

Autosomal DNA

Across all areas of Madagascar, the average ancestry for the Malagasy people was found to be 4% West Eurasian, 37% Austronesian, and 59% Bantu.

Medical DNA

The genomes of Africans commonly found to undergo adaptation are regulatory DNA, and many cases of adaptation found among Africans relate to diet, physiology, and evolutionary pressures from pathogens. Throughout Sub-Saharan Africa, genetic adaptation (e.g., rs334 mutation, Duffy blood group, increased rates of G6PD deficiency, sickle cell disease) to malaria has been found among Sub-Saharan Africans, which may have initially developed in 7300 BP. Sub-Saharan Africans have more than 90% of the Duffy-null genotype. In the highlands of Ethiopia, genetic adaptation (e.g., rs10803083, an SNP associated with the rate and function of hemoglobin; BHLHE41, a gene associated with circadian rhythm and hypoxia response; EGNL1, a gene strongly associated with oxygen homeostasis in mammals) to hypoxia and low atmospheric pressure has been found among the Amhara people, which may have developed within the past 5000 years. In Tanzania, genetic adaptation (e.g., greater amount of amylase genes than in African populations that consume low-starch foods) has been found in the Hadza people due to a food diet that especially includes consumption of tubers.

Southern Africa

Archaic Human DNA

While Denisovan and Neanderthal ancestry in non-Africans outside of Africa are more certain, archaic human ancestry in Africans is less certain and is too early to be established with certainty.

Ancient DNA

Three Later Stone Age hunter-gatherers carried ancient DNA similar to Khoisan-speaking hunter-gatherers. Prior to the Bantu migration into the region, as evidenced by ancient DNA from Botswana, East African herders migrated into Southern Africa. Out of four Iron Age Bantu agriculturalists of West African origin, two earlier agriculturalists carried ancient DNA similar to Tsonga and Venda peoples and the two later agriculturalists carried ancient DNA similar to Nguni people; this indicates that there were various movements of peoples in the overall Bantu migration, which resulted in increased interaction and admixing between Bantu-speaking peoples and Khoisan-speaking peoples.

Botswana

At Nqoma, in Botswana, an individual, dated to the Early Iron Age (900 BP), carried haplogroup L2a1f.

At Taukome, in Botswana, an individual, dated to the Early Iron Age (1100 BP), carried haplogroups E1b1a1 (E-M2, E-Z1123) and L0d3b1.

At Xaro, in Botswana, there were two individuals, dated to the Early Iron Age (1400 BP); one carried haplogroups E1b1a1a1c1a and L3e1a2, and another carried haplogroups E1b1b1b2b (E-M293, E-CTS10880) and L0k1a2.

Malawi

At Fingira rockshelter, in Malawi, an individual, dated between 6179 BP and 2341 BP, carried haplogroups B2 and L0d1.

At Chencherere, in Malawi, an individual, estimated to date between 5400 BP and 4800 BP, carried haplogroup L0k2.

At Hora 1 rockshelter, in Malawi, an individual, dated between 16,897 BP and 15,827 BP, carried haplogroups B2b and L5b.

South Africa

At Doonside, in South Africa, an individual, estimated to date between 2296 BP and 1910 BP, carried haplogroup L0d2.

At Ballito Bay, South Africa, an individual, estimated to date between 1986 BP and 1831 BP, carried haplogroups A1b1b2 and L0d2c1.

At Kalemba rockshelter, in Zambia, an individual, dated between 5285 BP and 4975 BP, carried haplogroup L0d1b2b.

Y-Chromosomal DNA

Various Y chromosome studies show that the San carry some of the most divergent (oldest) human Y-chromosome haplogroups. These haplogroups are specific sub-groups of haplogroups A and B, the two earliest branches on the human Y-chromosome tree.

Mitochondrial DNA

In 200,000 BP, Africans (e.g., Khoisan of Southern Africa) bearing haplogroup L0 diverged from other Africans bearing haplogroup L1′6, which tend to be northward of Southern Africa. Between 130,000 BP and 75,000 BP, behavioral modernity emerged among Southern Africans and long-term interactions between the regions of Southern Africa and Eastern Africa became established.

Mitochondrial DNA studies also provide evidence that the San carry high frequencies of the earliest haplogroup branches in the human mitochondrial DNA tree. This DNA is inherited only from one's mother. The most divergent (oldest) mitochondrial haplogroup, L0d, has been identified at its highest frequencies in the southern African San groups.

Autosomal DNA

Henn et al. (2011) found that the ǂKhomani San, as well as the Sandawe and Hadza peoples of Tanzania, were the most genetically diverse of any living humans studied. This high degree of genetic diversity hints at the origin of anatomically modern humans.

Medical DNA

Among the ancient DNA from three hunter-gatherers sharing genetic similarity with San people and four Iron Age agriculturalists, their SNPs indicated that they bore variants for resistance against sleeping sickness and Plasmodium vivax. In particular, two out of the four Iron Age agriculturalists bore variants for resistance against sleeping sickness and three out of the four Iron Age agriculturalists bore Duffy negative variants for resistance against malaria. In contrast to the Iron Age agriculturalists, from among the San-related hunter-gatherers, a six-year-old boy may have died from schistosomiasis. In Botswana, a man, who dates to 1400 BP, may have also carried the Duffy negative variant for resistance against malaria.

The genomes of Africans commonly found to undergo adaptation are regulatory DNA, and many cases of adaptation found among Africans relate to diet, physiology, and evolutionary pressures from pathogens. Throughout Sub-Saharan Africa, genetic adaptation (e.g., rs334 mutation, Duffy blood group, increased rates of G6PD deficiency, sickle cell disease) to malaria has been found among Sub-Saharan Africans, which may have initially developed in 7300 BP. Sub-Saharan Africans have more than 90% of the Duffy-null genotype. In the Kalahari Desert region of Africa, various possible genetic adaptations (e.g., adiponectin, body mass index, metabolism) have been found among the ǂKhomani people. Sub-Saharan Africans have more than 90% of the Duffy-null genotype. In South Africa, genetic adaptation (e.g., rs28647531 on chromosome 4q22) and strong susceptibility to tuberculosis has been found among Coloureds.

Recent African origin of modern humans

Between 500,000 BP and 300,000 BP, anatomically modern humans may have emerged in Africa. As Africans (e.g., Y-Chromosomal Adam, Mitochondrial Eve) have migrated from their places of origin in Africa to other locations in Africa, and as the time of divergence for East African, Central African, and West African lineages are similar to the time of divergence for the Southern African lineage, there is insufficient evidence to identify a specific region for the origin of humans in Africa. In 100,000 BP, anatomically modern humans migrated from Africa into Eurasia. Subsequently, tens of thousands of years after, the ancestors of all present-day Eurasians migrated from Africa into Eurasia and eventually became admixed with Denisovans and Neanderthals.

Archaeological and fossil evidence provide support for the African origin of homo sapiens and behavioral modernity. Models reflecting a pan-African origin (multiple locations of origin within Africa) and evolution of modern humans have been developed. As the idea of "modern" has become increasingly problematized, research has "begun to disentangle what is meant by "modern" genetic ancestry, skeletal morphology, and behavior, recognizing these are unlikely to form a single package."

In comparison to the non-African genome, the African genome features a ~25% greater number of polymorphisms, or 3 to 5 times as many, and genetic variants that are rare outside of Africa are found to occur at an abundant rate within Africa. Most of the genetic diversity found among non-Africans is found to be, at large, a subset of genetic diversity found among Africans. The genomes of Africans commonly found to undergo adaptation are regulatory DNA, and many cases of adaptation found among Africans relate to diet, physiology, and evolutionary pressures from pathogens. Throughout Sub-Saharan Africa, genetic adaptation (e.g., rs334 mutation, Duffy blood group, increased rates of G6PD deficiency, sickle cell disease) to malaria has been found among Sub-Saharan Africans, which may have initially developed in 7300 BP. Throughout Africa, various genetic adaptations (e.g., apolipoprotein L1 (APOL1): G1 and G2 haplotype resistance to trypanosomiasis and increased risk of kidney disease; human leukocyte antigen (HLA) genes; major histocompatibility complex (MHC)) to HIV-1, smallpox, trypanosomiasis (African sleeping sickness), and tuberculosis has been found among Africans. Biomedical tests for specific genetic variants (e.g., rs1799853 in the CYP2C9 gene), which have been approved by the U.S. Food and Drug Administration and are intended to indicate correct prescription of warfarin, has been found to be increasingly irrelevant to Africans as the variants are rare in Africa. As frequency rate factors into considering and deciding variant pathogenicity and generalizable polygenic scores, modern clinical classifications of genetic variant pathogenicity are found to be inadequate due to a lack of genetic diversity in biomedical studies. Fan et al (2023) recently found ~5.3 million unique genetic variants in 180 African hunter-gatherer populations, and among existing classifications for variants determined to likely be "pathogenic", ~29% (44/154) of these "pathogenic" classified variants were found to occur frequently among the African hunter-gatherers.

Human ethology

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Human_ethology

Human ethology is the study of human behavior. Ethology as a discipline is generally thought of as a sub-category of biology, though psychological theories have been developed based on ethological ideas (e.g. sociobiology, evolutionary psychology, attachment theory, and theories about human universals such as gender differences, incest avoidance, mourning, hierarchy and pursuit of possession). The bridging between biological sciences and social sciences creates an understanding of human ethology. The International Society for Human Ethology is dedicated to advancing the study and understanding of human ethology.

History

Ethology has its roots in the study of evolution, especially after evolution's increasing popularity after Darwin's detailed observations. It became a distinct discipline in the 1930s with zoologists Konrad Lorenz, Niko Tinbergen and Karl Von Frisch. These three scientists are known as the major contributors to human ethology. They are also regarded as the fathers or founders of ethology. Konrad Lorenz and Niko Tinbergen rejected theories that relied on stimuli and learning alone, and elaborated on concepts that had not been well understood, such as instinct. They promoted the theory that evolution had placed within creatures innate abilities and responses to certain stimuli that advanced the thriving of the species. Konrad Lorenz also indicated in his earlier works that animal behavior can be a major reference for human behavior. He believed that the research and findings of animal behaviors can lead to findings of human behaviors as well. In 1943, Lorenz devoted much of his book, Die angeborenen Formen moglicher Erfahrung, to human behavior. He designated that one of the most important factors of ethology was testing the hypothesis derived from animal behavioral studies on human behavioral studies. Due to Lorenz promoting the similarities between studying animal and human behavior, human ethology derived from the study of anima behavior. The other founders of ethology, Niko Tinbergen and Karl von Frisch, received a Nobel Prize in 1973, for their overarching career discoveries concerning organization and elicitation of individual and social behavior patterns.

Many developmental psychologists were eager to incorporate ethological principles into their theories as a way of explaining observable phenomenon in babies that could not necessarily be explained by learning or other concepts. John Bowlby and Mary Ainsworth used ethology prominently to explain aspects of infant-caretaker‍‍ attachment theory‍‍. Some important attachment concepts related to evolution:

The Attachment has evolved because it promotes the survival of helpless infants. Primates and other animals reflexively attach themselves physically to their parent, and have some calls that elicit parental attention. Human babies have adaptively developed signaling mechanisms such as crying, babbling, and smiling. These are seen as innate and not learned behaviors, because even children born blind and deaf begin to smile socially at 6 weeks, and cry and babble. These behaviors facilitate contact with the caregiver and increase the likelihood of infant survival.
Early signaling behaviors and the baby's tendency to look at faces rather than objects lead to attachment between the caretaker and baby that solidifies around 6–9 months of age. Bowlby theorized that this attachment was evolutionarily fundamental to human survival and is the basis for all relationships, even into adulthood.
Adults are also adaptively bent toward attachment with infants. Typical "baby-ish" features, such as a large head and eyes in proportion to the body, and round cheeks, are features that elicit affection in adults. Many parents also form a "bond" with their newborn baby within hours of its birth, leading to a deep sense of emotional attachment with one's own offspring and increased behaviors that promote infant survival.
Many of Bowlby's early methods relied heavily on ethological observations of children in their natural environments.

In later years, ethology played a large role in sociobiological theory and ultimately, in evolutionary psychology, which is a relatively new field of study. Evolutionary psychology combines ethology, primatology, anthropology, and other fields to study modern human behavior to adaptive ancestral human behaviors.

View on human nature‍‍

Humans are social animals. Just as wolves and lions create packs or hunting groups for self-preservation, humans create complex social structures, including families and nations.
Humans are "biological organisms that have evolved within a particular environmental niche".
Intelligence, language, social attachment, aggression, and altruism are part of human nature because they "serve or once served a purpose in the struggle of the species to survive".
Children's developmental level is defined in terms of biologically based behaviors.
Human's needs evolve based on their current environment. Humans must adapt in order to survive. Cognitive thinking and communication arose as a result of a need for cooperation amongst individuals for survival.

View on human nature varies across ethological theorists

Lorenz believed that humans have an automatic, elicited nature of behavior, such as stimuli that elicit fixed action patterns.‍‍ His theory developed from the reflex model and the hydraulic or "flush toilet" model‍‍, which conceptualized behavior patterns of motivation. Certain fixed action patterns developed out of motivation for survival. Instinct is an example of fixed action patterns. Any behavior is instinctive if it is performed in the absence of learning. Reflexes can be instincts. For example, a newborn baby instinctively knows to search for and suckle its mother's breast for ‍‍nourishment. ‍‍
Bowlby (and many other modern ethological theorists) believed that humans spontaneously act to meet the demands of their environment. They are active participants who seek out a parent, food, or a mate (i.e. an infant will seek to remain within sight of a‍‍ caretaker)‍‍.
Vygotsky believed that the way humans think is based on the culture they are raised in and the language they are surrounded by. He emphasized that children grow up in the symbols of their culture, especially linguistic symbols. These linguistic symbols categorize and organize the world around them. This organization of the world is internalized, which influence the way they think.
Human behavior tends to change based on the environment and the surrounding challenges that individuals begin to face. Two evolutionary advances in human behavior began as a way to allow humans to communicate and collaborate. Infrastructure theorist, Mead and Wittgenstein, theorized the creation of a collaboration in human foraging. This collaboration created social goals amongst people and also created a common ground. To coordinate their common goals, humans evolved a new type of cooperative communication. This communication was based on gestures that allowed humans to cooperate amongst themselves in order to achieve their desired goals. This change in behavior is seen due to the evolving of their environment. The environment demands survival and humans adapted their behavior in order to survive. In other words, this is known as the shared intentionality hypothesis. According to this hypothesis, human thinking evolved from a self-focused, individual intentionality as an adaptation for "dealing with problems of social coordination, specifically, problems presented by individuals' attempts to collaborate and communicate with others." This evolution happened in two steps, one leading from individual to "joint intentionality" and the other from joint intentionality to "collective intentionality".
Mechanistic theories view behavior as passive. This theory argues that human behavior is in passivity through physiological drives and emotional stimuli. Unlike mechanistic theories, organismic theories view behavior as active. An organismic theory argues that an organism is active in its behavior, meaning that it decides how it behaves and initiates its own behaviors. Humans have intrinsic needs that they desire to be met. These needs provide energy for humans to act upon their needs in order to meet them, rather than being reactive to them. The active theory on human behavior treats stimuli not as a cause of behavior, but as opportunities humans can utilize to meet their demands.

Human ethology topics

As applied to human behavior, in the majority of cases, topical behavior results from motivational states and the intensity of a specific external stimulus. Organisms with a high inner motivational state for such a stimulus is called appetitive behavior. Other important concepts of zooethology—e.g., territoriality, hierarchy, sensitive periods in ontogenesis—are also useful when discussing human behavior. Irenäus Eibl-Eibesfeldt's book Human Ethology is most important for how these concepts are applied to human behavior.

Human ethology has contributed in two particular ways to our understanding of the ontogeny of behavior in humans. This has resulted, first, from the application of techniques for the precise observation, description and classification of naturally occurring behavior and, secondly, from the ethological approach to the study of behavior, especially the development of behavior in terms of evolution. Of particular interest are questions relating to the function of a particular kind of behavior (e.g., attachment behavior) and its adaptive value. The description of the behavioral repertoire of a species, the recognition of patterns of behavioral development and the classification of established behavioral patterns are prerequisites for any comparison between different species or between organisms of a single species. The ethological approach is the study of the interaction between the organism with certain innate species-specific structures and the environment for which the organism is genetically programmed.

Invariant behavior patterns have a morphological basis, mainly in neuronal structures common to all members of a species and, depending on the kind of behavior, may also be common to a genus or family or a whole order, e.g., primates, or even to a whole class, e.g., mammals. In such structures we can retrace and follow the evolutionary process by which the environment produced structures, especially nervous systems and brains, which generate adaptive behavior. In organisms with a high level of organization, the processes in which the ethologist is especially interested are those genetically preprogrammed motor and perceptual processes that facilitate social interaction and communication, such as facial expression and vocalization. If we consider the most highly developed means of communication, language and speech, which is found in humans alone, the question arises as to the biological foundation of this species-specific behavior and perceptual skill. The ethologist examines this question primarily from the point of view of ontogenetic development.

The main strength of human ethology has been its application of established interpretive patterns to new problems. Based on theories, concepts and methods that have proved successful in animal ethology, it looks at human behavior from a new viewpoint. The essence of this is the evolutionary perspective. But since ethologists have been relatively unaffected by the long history of the humanities, they often refer to facts and interpretations neglected by other social sciences. If we look back at the history of the relationship between the life sciences and the social sciences, we find two prevailing modes of theoretical orientation: on the one hand, reductionism, i.e., attempts to reduce human action to non-cognitive behavior; and on the other, attempts to separate human action and human society from the animal world completely. The advent of the theory of evolution in the 19th century brought no easy solution to the problem of nature and nurture, since it could still be "solved" in either a continuous or discontinuous manner. Human ethology as much as any other discipline significantly contributes to the obsolescence of such simple dichotomies.

Human Ethology has an increasing influence on the dialogue between Human Sciences and Humanities as shown for example in the book Being Human - Bridging the Gap between the Sciences of Body and Mind.

Methodology

‍‍Ethologists‍‍ study behavior using two general methods: naturalistic observation and laboratory experimentation. Ethologist's insistence on observing organisms in their natural environment differentiates ethology from related disciplines such as evolutionary psychology and sociobiology, and their naturalistic observation "ranks as one of their main contributions to psychology", Naturalistic Observation Ethologists believe that in order to study species-specific behaviors, a species must be observed in its natural environment. One can only understand the function of a behavior by seeing how it specifically fits into the ‍‍species‍‍ natural environment to fulfill a specific need. Ethologists follow a specific set of steps when studying an organism:

Ethogram	A detailed description of the behavior of a species in its natural environment
Classification	Classify behaviors according to their function (how they encourage survival).
Compare	Compare how a behavior functions in different species and how different behaviors may serve the same function in other species.
Laboratory Experiments	Determine the immediate causes of the behavior described in the first three steps.

These steps fall in line with Tinbergen's "On Aims of Methods of Ethology" in which he states that every study of behavior must answer four questions to be considered legitimate:

function (adaptation)
evolution (phylogeny)
causation (mechanism)
development (ontogeny)

Diversity

Diversity is an important concept in ethology and evolutionary theory, both genetically and culturally.

Genetic diversity serves as a way for populations to adapt to changing environments. With more variation, it is more likely that some individuals in a population will possess variations of alleles that are suited for the environment. Those individuals are more likely to survive to produce offspring bearing that allele. The population will continue for more generations because of the success of these individuals. Population genetics includes several hypotheses and theories regarding genetic diversity. The neutral theory of evolution proposes that diversity is the result of the accumulation of neutral substitutions. Diversifying selection is the hypothesis that two subpopulations of a species live in different environments that select for different alleles at a particular locus. This may occur, for instance, if a species has a large range relative to the mobility of individuals within it.

Cultural diversity is also important. From a cultural transmission standpoint, humans are the only animals to pass down cumulative cultural knowledge to their offspring. While chimpanzees can learn to use tools by watching other chimps around them, but humans are able to pool their cognitive resources to create increasingly more complex solutions to problems and more complex ways of interacting with their environments. The diversity of cultures points to the idea that humans are shaped by their environments, and also interact with environments to shape them as well. Cultural diversity arises from different human adaptations to different environmental factors, which in turn shapes the environment, which in turn again shapes human behavior. This cycle results in diverse cultural representations that ultimately add to the survival of the human species. This approach is important as a way to build a bridge between biological and social sciences, which creates a better understanding of human ethology.

One example of human diversity is sexual orientation. Ethologists have long noted that there are over 250 species of animals which display homosexual behaviors. Although no offspring are directly created from homosexual behaviors, a closer look reveals how the genes for homosexuality can persist. Homosexuality could decrease competition for heterosexual mates. Homosexual family members could increase the resources available to the children of their siblings without producing offspring to compete for those resources (the gay uncle theory), thus creating better chances for their siblings' offspring to survive. These related offspring share the homosexual individual's genes—although to a lesser extent than direct offspring would—including genes for homosexuality. This causes a small but stable chance for future generations to be gay as well, even if the gay family member produces no direct descendants.

Thursday, October 16, 2025

Modularity of mind

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Modularity_of_mind

Modularity of mind is the notion that a mind may, at least in part, be composed of innate neural structures or mental modules which have distinct, established, and evolutionarily developed functions. However, different definitions of "module" have been proposed by different authors. According to Jerry Fodor, the author of Modularity of Mind, a system can be considered 'modular' if its functions are made of multiple dimensions or units to some degree. One example of modularity in the mind is binding. When one perceives an object, they take in not only the features of an object, but the integrated features that can operate in sync or independently that create a whole. Instead of just seeing red, round, plastic, and moving, the subject may experience a rolling red ball. Binding may suggest that the mind is modular because it takes multiple cognitive processes to perceive one thing.

Early investigations

Historically, questions regarding the functional architecture of the mind have been divided into two different theories of the nature of the faculties. The first can be characterized as a horizontal view because it refers to mental processes as if they are interactions between faculties such as memory, imagination, judgement, and perception, which are not domain specific (e.g., a judgement remains a judgement whether it refers to a perceptual experience or to the conceptualization/comprehension process). The second can be characterized as a vertical view because it claims that the mental faculties are differentiated on the basis of domain specificity, are genetically determined, are associated with distinct neurological structures, and are computationally autonomous.

The vertical vision goes back to the 19th-century movement called phrenology and its founder Franz Joseph Gall. Gall claimed that the individual mental faculties could be associated precisely, in a one-to-one correspondence, with specific physical areas of the brain. For example, someone's level of intelligence could be literally "read off" from the size of a particular bump on his posterior parietal lobe. Phrenology's practice was debunked scientifically by Pierre Flourens in the 19th century. He destroyed parts of pigeons' and dogs' brains, called lesions, and studied the organisms' resulting dysfunction. He was able to conclude that while the brain localizes in some functions, it also works as a unit and is not as localized as earlier phrenologists thought. Before the early 20th century, Edward Bradford Titchener studied the modules of the mind through introspection. He tried to determine the original, raw perspective experiences of his subjects. For example, if he wanted his subjects to perceive an apple, they would need to talk about spatial characteristics of the apple and the different hues that they saw without mentioning the apple.

Fodor's Modularity of Mind

In the 1980s, however, Jerry Fodor revived the idea of the modularity of mind, although without the notion of precise physical localizability. Drawing from Noam Chomsky's idea of the language acquisition device and other work in linguistics as well as from the philosophy of mind and the implications of optical illusions, he became a major proponent of the idea with the 1983 publication of Modularity of Mind.

According to Fodor, a module falls somewhere between the behaviorist and cognitivist views of lower-level processes.

Behaviorists tried to replace the mind with reflexes, which are, according to Fodor, encapsulated (cognitively impenetrable or unaffected by other cognitive domains) and non-inferential (straight pathways with no information added). Low-level processes are unlike reflexes in that they can be inferential. This can be demonstrated by poverty of the stimulus argument, which posits that children do not only learn language from their environment, but are innately programmed with low-level processes that help them seek and learn language. The proximate stimulus, that which is initially received by the brain (such as the 2D image received by the retina), cannot account for the resulting output (for example, our 3D perception of the world), thus necessitating some form of computation.

In contrast, cognitivists saw lower-level processes as continuous with higher-level processes, being inferential and cognitively penetrable (influenced by other cognitive domains, such as beliefs). The latter has been shown to be untrue in some cases, such as the Müller-Lyer illusion, which can persist despite a person's awareness of their existence. This is taken to indicate that other domains, including one's beliefs, cannot influence such processes.

Fodor arrives at the conclusion that such processes are inferential like higher-order processes and encapsulated in the same sense as reflexes.

Although he argued for the modularity of "lower level" cognitive processes in Modularity of Mind he also argued that higher-level cognitive processes are not modular since they have dissimilar properties. The Mind Doesn't Work That Way, a reaction to Steven Pinker's How the Mind Works, is devoted to this subject.

Fodor (1983) states that modular systems must—at least to "some interesting extent"—fulfill certain properties:

Domain specificity: modules only operate on certain kinds of inputs—they are specialised
Obligatory firing: modules process in a mandatory manner
Limited accessibility: what central processing can access from input system representations is limited
Fast speed: probably due to the fact that they are encapsulated (thereby needing only to consult a restricted database) and mandatory (time need not be wasted in determining whether or not to process incoming input)
Informational encapsulation: modules need not refer to other psychological systems in order to operate
Shallow outputs: the output of modules is very simple
Specific breakdown patterns
Characteristic ontogeny: there is a regularity of development
Fixed neural architecture.

Pylyshyn (1999) has argued that while these properties tend to occur with modules, one—information encapsulation—stands out as being the real signature of a module; that is the encapsulation of the processes inside the module from both cognitive influence and from cognitive access. One example is that conscious awareness that the Müller-Lyer illusion is an illusion does not correct visual processing.

Evolutionary psychology and massive modularity

The definition of module has caused confusion and dispute. In J.A. Fodor's views, modules can be found in peripheral and low-level visual processing, but not in central processing. Later, he narrowed the two essential features to domain-specificity and information encapsulation. According to Frankenhuis and Ploeger, domain-specificity means that "a given cognitive mechanism accepts, or is specialized to operate on, only a specific class of information". Information encapsulation means that information processing in the module cannot be affected by information in the rest of the brain. One example is that the effects of an optical illusion, created by low-level processes, persist despite high-level processing caused by conscious awareness of the illusion itself.

Other perspectives on modularity come from evolutionary psychology. Evolutionary psychologists propose that the mind is made up of genetically influenced and domain-specific mental algorithms or computational modules, designed to solve specific evolutionary problems of the past. Modules are also used for central processing. This theory is sometimes referred to as massive modularity. Leda Cosmides and John Tooby claimed that modules are units of mental processing that evolved in response to selection pressures. To them, each module was a complex computer that innately processed distinct parts of the world, like facial recognition, recognizing human emotions, and problem-solving. On this view, much modern human psychological activity is rooted in adaptations that occurred earlier in human evolution, when natural selection was forming the modern human species.

A 2010 review by evolutionary psychologists Confer et al. suggested that domain general theories, such as for "rationality", has several problems: 1. Evolutionary theories using the idea of numerous domain-specific adaptions have produced testable predictions that have been empirically confirmed; the theory of domain-general rational thought has produced no such predictions or confirmations. 2. The rapidity of responses such as jealousy due to infidelity indicates a domain-specific dedicated module rather than a general, deliberate, rational calculation of consequences. 3. Reactions may occur instinctively (consistent with innate knowledge) even if a person has not learned such knowledge. One example being that in the ancestral environment it is unlikely that males during development learn that infidelity (usually secret) may cause paternal uncertainty (from observing the phenotypes of children born many months later and making a statistical conclusion from the phenotype dissimilarity to the cuckolded fathers). With respect to general purpose problem solvers, Barkow, Cosmides, and Tooby (1992) have suggested in The Adapted Mind: Evolutionary Psychology and The Generation of Culture that a purely general problem solving mechanism is impossible to build due to the frame problem. Clune et al. (2013) have argued that computer simulations of the evolution of neural nets suggest that modularity evolves because, compared to non-modular networks, connection costs are lower.

Several groups of critics, including psychologists working within evolutionary frameworks, argue that the massively modular theory of mind does little to explain adaptive psychological traits. Proponents of other models of the mind argue that the computational theory of mind is no better at explaining human behavior than a theory with mind entirely a product of the environment. Even within evolutionary psychology there is discussion about the degree of modularity, either as a few generalist modules or as many highly specific modules. Other critics suggest that there is little empirical support in favor of the domain-specific theory beyond performance on the Wason selection task, a task critics state is too limited in scope to test all relevant aspects of reasoning.Moreover, critics argue that Cosmides and Tooby's conclusions contain several inferential errors and that the authors use untested evolutionary assumptions to eliminate rival reasoning theories.

Criticisms of the notion of modular minds from genetics include that it would take too much genetic information to form innate modularity of mind, the limits to the possible amount of functional genetic information being imposed by the number of mutations per generation that led to the prediction that only a small part of the human genome can be functional in an information-carrying way if an impossibly high rate of lethal mutations is to be avoided, and that selection against lethal mutations would have stopped and reversed any increase in the amount of functional DNA long before it reached the amount that would be required for modularity of mind. It is argued that proponents of the theory of mind conflate this with the straw man argument of assuming no function in any non-protein-coding DNA when pointing at discoveries of some parts of non-coding DNA having regulatory functions, while the actual argument of limited amount of functional DNA does acknowledge that some parts of non-coding DNA can have functions but putting bounds on the total amount of information-bearing genetic material regardless of whether or not it codes for proteins, in agreement with the discoveries of regulatory functions of non-coding DNA extending only to parts of it and not be generalized to all DNA that does not code for proteins. The maximum amount of information-carrying heredity is argued to be too small to form modular brains.

Wallace (2010) observes that the evolutionary psychologists' definition of "mind" has been heavily influenced by cognitivism and/or information processing definitions of the mind. Critics point out that these assumptions underlying evolutionary psychologists' hypotheses are controversial and have been contested by some psychologists, philosophers, and neuroscientists. For example, Jaak Panksepp, an affective neuroscientist, point to the "remarkable degree of neocortical plasticity within the human brain, especially during development" and states that "the developmental interactions among ancient special-purpose circuits and more recent general-purpose brain mechanisms can generate many of the "modularized" human abilities that evolutionary psychology has entertained."

Philosopher David Buller agrees with the general argument that the human mind has evolved over time but disagrees with the specific claims evolutionary psychologists make. He has argued that the contention that the mind consists of thousands of modules, including sexually dimorphic jealousy and parental investment modules, are unsupported by the available empirical evidence. He has suggested that the "modules" result from the brain's developmental plasticity and that they are adaptive responses to local conditions, not past evolutionary environments. However, Buller has also stated that even if massive modularity is false this does not necessarily have broad implications for evolutionary psychology. Evolution may create innate motives even without innate knowledge.

In contrast to modular mental structure, some theories posit domain-general processing, in which mental activity is distributed across the brain and cannot be decomposed, even abstractly, into independent units. A staunch defender of this view is William Uttal, who argues in The New Phrenology (2003) that there are serious philosophical, theoretical, and methodological problems with the entire enterprise of trying to localise cognitive processes in the brain. Part of this argument is that a successful taxonomy of mental processes has yet to be developed.

Merlin Donald argues that over evolutionary time the mind has gained adaptive advantage from being a general problem solver. The mind, as described by Donald, includes module-like "central" mechanisms, in addition to more recently evolved "domain-general" mechanisms.

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Friday, October 17, 2025

Genetic history of Africa

Overview

Indigenous Africans

Out-of-Africa event

Geneflow between Eurasian and African populations

Horn of Africa

Madagascar

Northern Africa

Western Africa

Southern Africa

Regional genomic overview

North Africa

Archaic Human DNA

Ancient DNA

Egypt

Libya

Morocco

Y-Chromosomal DNA

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Lactase persistence

West Africa

Archaic Human DNA

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Y-Chromosomal DNA

Mitochondrial DNA

Autosomal DNA

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Pediculus

Sickle Cell

Schistosomes

Thalassemia

Domesticated Animal DNA

Central Africa

Archaic Human DNA

Ancient DNA

Cameroon

Democratic Republic of Congo

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Mitochondrial DNA

Autosomal DNA

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Eastern Africa

Archaic Human DNA

Ancient DNA

Ethiopia

Kenya

Tanzania

Uganda

Y-Chromosomal DNA

Mitochondrial DNA

Autosomal DNA

Medical DNA

Southern Africa

Archaic Human DNA

Ancient DNA

Botswana

Malawi

South Africa

Y-Chromosomal DNA

Mitochondrial DNA

Autosomal DNA

Medical DNA

Recent African origin of modern humans

Human ethology

History

View on human nature‍‍

View on human nature varies across ethological theorists

Human ethology topics

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Thursday, October 16, 2025

Modularity of mind

Early investigations

Fodor's Modularity of Mind

Evolutionary psychology and massive modularity

Quantum chemistry