Cladogram (family tree) of a biological group. The green box (central) may represent an evolutionary grade (paraphyletic),
a group united by conservative anatomical and physiological traits
rather than phylogeny. The flanking red and blue boxes are clades (i.e., complete monophyletic subtrees).
In order to fully understand evolutionary grades, one must first get a better understanding of phylogenetics: the study of the evolutionary history and relationships among or within groups of organisms. These relationships are determined by phylogenetic inference methods that focus on observed heritable traits, such as DNA sequences, proteinamino acid sequences, or morphology. The result of such an analysis is a phylogenetic tree—a diagram containing a hypothesis of relationships that reflects the evolutionary history of a group of organisms.
Definition of an evolutionary grade
An evolutionary grade is a group of species united by morphological or physiological
traits, that has given rise to another group that has major differences
from the ancestral group's condition, and is thus not considered part
of the ancestral group, while still having enough similarities that we
can group them under the same clade.[clarification needed] The ancestral group will not be phylogenetically complete (i.e. is not a clade), and so will represent a paraphyletic taxon.
The most commonly cited example is that of reptiles. In the early 19th century, the French naturalist Latreille was the first to divide tetrapods into the four familiar classes of amphibians, reptiles, birds, and mammals. In this system, reptiles are characterized by traits such as laying membranous or shelled eggs, having skin covered in scales or scutes, and having a 'cold-blooded'
metabolism. However, the ancestors of mammals and birds also had these
traits and so birds and mammals can be said to "have evolved from
reptiles", making the reptiles, when defined by these traits, a grade
rather than a clade. In microbiology, taxa that are thus seen as excluded from their evolutionary grade parent group are called taxa in disguise.
Paraphyletic taxa will often, but not always, represent
evolutionary grades. In some cases paraphyletic taxa are united simply
by not being part of any other groups, and give rise to so-called wastebasket taxa which may even be polyphyletic.
The traditional Linnaean
way of defining taxa is through the use of anatomical traits. When the
actual phylogenetic relationship is unknown, well defined groups
sometimes turn out to be defined by traits that are primitive rather
than derived. In Linnaean systematics, evolutionary grades are accepted in higher taxonomic ranks, though generally avoided at family level and below. In phylogenetic nomenclature evolutionary grades (or any other form of paraphyly) are not accepted.
Where information about phylogenetic relationships is available, organisms are preferentially grouped into clades.
Where data is lacking, or groups of uncertain relationship are to be
compared, the cladistic method is limited and grade provides a useful
tool for comparing organisms. This is particularly common in palaeontology, where fossils
are often fragmentary and difficult to interpret. Thus, traditional
palaeontological works are often using evolutionary grades as formal or
informal taxa, including examples such as labyrinthodonts, anapsids, synapsids, dinosaurs, ammonites, eurypterids, lobopodians and many of the more well known taxa of human evolution.
Organizing organisms into grades rather than strict clades can also be
very useful to understand the evolutionary sequence behind major
diversification of both animals and plants.
Evolutionary grades, being united by gross morphological traits, are often eminently recognizable in the field. While taxonomy
seeks to eliminate paraphyletic taxa, such grades are sometimes kept as
formal or informal groups on the basis of their usefulness for laymen
and field researchers. In bacteriology,
the renaming of species or groups that turn out to be evolutionary
grades is kept to a minimum to avoid misunderstanding, which in the case
of pathogens
could have fatal consequences. When referring to a group of organisms,
the term "grade" is usually enclosed in quotation marks to denote its
status as a paraphyletic term.
Grades and phylogenetic nomenclature
With the rise of phylogenetic nomenclature, the use of evolutionary grades as formal taxa has come under debate. Under a strict phylogenetic approach, only monophyletic taxa are recognized. This differs from the more traditional approach of evolutionary taxonomy.
The difference in approach has led to a vigorous debate between
proponents of the two approaches to taxonomy, particularly in well
established fields like vertebrate palaeontology and botany.
The difference between the statement "B is part of A" (phylogenetic
approach) and "B has evolved from A" (evolutionary approach) is,
however, one of semantics
rather than of phylogeny. Both express the same phylogeny, but the
former emphasizes the phylogenetic continuum while the latter emphasizes
a distinct shift in anatomy or ecology in B relative to A.
Dinosaurs were proposed to be the ancestors of birds as early as the 1860s. Yet the term sees popular use as an evolutionary grade excluding birds, though most scientists use a monophyletic Dinosauria.
Lizards represent an evolutionary grade, defined by their retention of limbs relative to snakes and amphisbaenians. However, defining lizards by the presence of limbs is incorrect, as there are many species of legless lizards, which are considered true lizards.
Prokaryotes, which include cellular organisms lacking a nucleus, represent a grade, since they are the ancestors of eukaryotes, which includes animals, plants, fungi, and protists; and the last of these four groups also represents a grade, since it excludes the previous three groups.
Crustaceans represent a grade, since they are the ancestors of hexapods, which includes insects and related taxa.
Monkeys represent a grade, since they include the ancestors of apes (including humans).
Likewise, apes represent a grade in common usage, but are a clade if humans are included.
The eukaryotes seemingly emerged in the Archaea, within the Asgard archaea. This implies that there are only two domains of life,
Bacteria and Archaea, with eukaryotes incorporated among the Archaea.
Eukaryotes emerged approximately 2.2 billion years ago, during the Proterozoic eon, likely as flagellated cells. The leading evolutionary theory is they were created by symbiogenesis between an anaerobic Asgard archaean and an aerobic proteobacterium, which formed the mitochondria. A second episode of symbiogenesis with a cyanobacterium created the plants, with chloroplasts.
Eukaryotes are organisms that range from microscopic single cells, such as picozoans under 3 micrometres across, to animals like the blue whale, weighing up to 190 tonnes and measuring up to 33.6 metres (110 ft) long, or plants like the coast redwood, up to 120 metres (390 ft) tall. Many eukaryotes are unicellular; the informal grouping called protists includes many of these, with some multicellular forms like the giant kelp up to 200 feet (61 m) long. The multicellular eukaryotes include the animals, plants, and fungi, but again, these groups too contain many unicellular species. Eukaryotic cells are typically much larger than those of prokaryotes—the bacteria and the archaea—having a volume of around 10,000 times greater. Eukaryotes represent a small minority of the number of organisms, but, as many of them are much larger, their collective global biomass
(468 gigatons) is far larger than that of prokaryotes (77 gigatons),
with plants alone accounting for over 81% of the total biomass of Earth.
Eukaryotes range in size from single cells to organisms weighing many tons
The defining feature of eukaryotes is that their cells have nuclei. This gives them their name, from the Greekεὖ (eu, "well" or "good") and κάρυον (karyon, "nut" or "kernel", here meaning "nucleus"). Eukaryotic cells have a variety of internal membrane-bound structures, called organelles, and a cytoskeleton which defines the cell's organization and shape. The nucleus stores the cell's DNA, which is divided into linear bundles called chromosomes; these are separated into two matching sets by a microtubular spindle during nuclear division, in the distinctively eukaryotic process of mitosis.
Biochemistry
Eukaryotes differ from prokaryotes in multiple ways, with unique biochemical pathways such as sterane synthesis. The eukaryotic signature proteins
have no homology to proteins in other domains of life, but appear to be
universal among eukaryotes. They include the proteins of the
cytoskeleton, the complex transcription machinery, the membrane-sorting systems, the nuclear pore, and some enzymes in the biochemical pathways.
Eukaryotic cells are some 10,000 times larger than prokaryotic cells by volume, and contain membrane-bound organelles.
Eukaryote cells include a variety of membrane-bound structures, together forming the endomembrane system. Simple compartments, called vesicles and vacuoles, can form by budding off other membranes. Many cells ingest food and other materials through a process of endocytosis, where the outer membrane invaginates and then pinches off to form a vesicle. Some cell products can leave in a vesicle through exocytosis.
The nucleus is surrounded by a double membrane known as the nuclear envelope, with nuclear pores that allow material to move in and out. Various tube- and sheet-like extensions of the nuclear membrane form the endoplasmic reticulum, which is involved in protein transport and maturation. It includes the rough endoplasmic reticulum, covered in ribosomes
which synthesize proteins; these enter the interior space or lumen.
Subsequently, they generally enter vesicles, which bud off from the
smooth endoplasmic reticulum. In most eukaryotes, these protein-carrying vesicles are released and further modified in stacks of flattened vesicles (cisternae), the Golgi apparatus.
Mitochondria are essentially universal in the eukaryotes, and with their own DNA somewhat resemble prokaryotic cells.
Mitochondria are organelles in eukaryotic cells. The mitochondrion is commonly called "the powerhouse of the cell", for its function providing energy by oxidising sugars or fats to produce the energy-storing molecule ATP. Mitochondria have two surrounding membranes, each a phospholipid bilayer; the inner of which is folded into invaginations called cristae where aerobic respiration takes place.
Mitochondria contain their own DNA, which has close structural similarities to bacterial DNA, from which it originated, and which encodes rRNA and tRNA genes that produce RNA which is closer in structure to bacterial RNA than to eukaryote RNA.
Some eukaryotes, such as the metamonadsGiardia and Trichomonas, and the amoebozoan Pelomyxa, appear to lack mitochondria, but all contain mitochondrion-derived organelles, like hydrogenosomes or mitosomes, having lost their mitochondria secondarily. They obtain energy by enzymatic action in the cytoplasm.
Plants and various groups of algae have plastids as well as mitochondria. Plastids, like mitochondria, have their own DNA and are developed from endosymbionts, in this case cyanobacteria. They usually take the form of chloroplasts which, like cyanobacteria, contain chlorophyll and produce organic compounds (such as glucose) through photosynthesis.
Others are involved in storing food. Although plastids probably had a
single origin, not all plastid-containing groups are closely related.
Instead, some eukaryotes have obtained them from others through secondary endosymbiosis or ingestion. The capture and sequestering of photosynthetic cells and chloroplasts, kleptoplasty, occurs in many types of modern eukaryotic organisms.
The cytoskeleton provides stiffening structure and points of
attachment for motor structures that enable the cell to move, change shape, or transport materials. The motor structures are microfilaments of actin and actin-binding proteins, including α-actinin, fimbrin, and filamin are present in submembranous cortical layers and bundles. Motor proteins of microtubules, dynein and kinesin, and myosin of actin filaments, provide dynamic character of the network.
Many eukaryotes have long slender motile cytoplasmic projections, called flagella, or multiple shorter structures called cilia. These organelles are variously involved in movement, feeding, and sensation. They are composed mainly of tubulin, and are entirely distinct from prokaryotic flagella. They are supported by a bundle of microtubules arising from a centriole, characteristically arranged as nine doublets surrounding two singlets. Flagella may have hairs (mastigonemes), as in many Stramenopiles. Their interior is continuous with the cell's cytoplasm.
Centrioles are often present, even in cells and groups that do not have flagella, but conifers and flowering plants
have neither. They generally occur in groups that give rise to various
microtubular roots. These form a primary component of the cytoskeleton,
and are often assembled over the course of several cell divisions, with
one flagellum retained from the parent and the other derived from it.
Centrioles produce the spindle during nuclear division.
The cells of plants, algae, fungi and most chromalveolates, but not animals, are surrounded by a cell wall. This is a layer outside the cell membrane, providing the cell with structural support, protection, and a filtering mechanism. The cell wall also prevents over-expansion when water enters the cell.
Eukaryotes have a life cycle that involves sexual reproduction, alternating between a haploid phase, where only one copy of each chromosome is present in each cell, and a diploid phase, with two copies of each chromosome in each cell. The diploid phase is formed by fusion of two haploid gametes, such as eggs and spermatozoa, to form a zygote; this may grow into a body, with its cells dividing by mitosis, and at some stage produce haploid gametes through meiosis, a division that reduces the number of chromosomes and creates genetic variability. There is considerable variation in this pattern. Plants have both haploid and diploid multicellular phases.
Eukaryotes have lower metabolic rates and longer generation times than
prokaryotes, because they are larger and therefore have a smaller
surface area to volume ratio.
The evolution of sexual reproduction may be a primordial characteristic of eukaryotes. Based on a phylogenetic analysis, Dacks and Roger have proposed that facultative sex was present in the group's common ancestor. A core set of genes that function in meiosis is present in both Trichomonas vaginalis and Giardia intestinalis, two organisms previously thought to be asexual.
Since these two species are descendants of lineages that diverged early
from the eukaryotic evolutionary tree, core meiotic genes, and hence
sex, were likely present in the common ancestor of eukaryotes. Species once thought to be asexual, such as Leishmania parasites, have a sexual cycle. Amoebae, previously regarded as asexual, are anciently sexual; present-day asexual groups likely arose recently.
Evolution
Tree
of eukaryotes showing major subgroups and thumbnail diagrams of
representative members of each group. Updated synthesis based on recent
(as of 2023) phylogenomic reconstructions.
In antiquity, the two lineages of animals and plants were recognized by Aristotle and Theophrastus. The lineages were given the taxonomic rank of Kingdom by Linnaeus in the 18th century. Though he included the fungi with plants with some reservations, it was later realized that they are quite distinct and warrant a separate kingdom.
The various single-cell eukaryotes were originally placed with plants
or animals when they became known. In 1818, the German biologist Georg A. Goldfuss coined the word protozoa to refer to organisms such as ciliates, and this group was expanded until Ernst Haeckel made it a kingdom encompassing all single-celled eukaryotes, the Protista, in 1866. The eukaryotes thus came to be seen as four kingdoms:
The protists were at that time thought to be "primitive forms", and thus an evolutionary grade, united by their primitive unicellular nature. Understanding of the oldest branchings in the tree of life only developed substantially with DNA sequencing, leading to a system of domains rather than kingdoms as top level rank being put forward by Carl Woese, Otto Kandler, and Mark Wheelis in 1990, uniting all the eukaryote kingdoms in the domain "Eucarya", stating, however, that "'eukaryotes' will continue to be an acceptable common synonym". In 1996, the evolutionary biologist Lynn Margulis
proposed to replace Kingdoms and Domains with "inclusive" names to
create a "symbiosis-based phylogeny", giving the description "Eukarya
(symbiosis-derived nucleated organisms)".
Phylogeny
By 2014, a rough consensus started to emerge from the phylogenomic studies of the previous two decades. The majority of eukaryotes can be placed in one of two large clades dubbed Amorphea (similar in composition to the unikont hypothesis) and the Diphoda (formerly bikonts), which includes plants and most algal lineages. A third major grouping, the Excavata, has been abandoned as a formal group as it is paraphyletic. The proposed phylogeny below includes only one group of excavates (Discoba), and incorporates the 2021 proposal that picozoans are close relatives of rhodophytes. The Provora are a group of microbial predators discovered in 2022. The Metamonada are hard to place, being sister possibly to Discoba, possibly to Malawimonada.
The origin of the eukaryotic cell, or eukaryogenesis, is a
milestone in the evolution of life, since eukaryotes include all complex
cells and almost all multicellular organisms. The last eukaryotic common ancestor (LECA) is the hypothetical origin of all living eukaryotes, and was most likely a biological population, not a single individual. The LECA is believed to have been a protist with a nucleus, at least one centriole and flagellum, facultatively aerobic mitochondria, sex (meiosis and syngamy), a dormant cyst with a cell wall of chitin or cellulose, and peroxisomes.
The presence of eukaryotic biomarkers in archaea points towards an archaeal origin. The genomes of Asgard archaea have plenty of Eukaryotic signature protein genes, which play a crucial role in the development of the cytoskeleton and complex cellular structures characteristic of eukaryotes. In 2022, cryo-electron tomography demonstrated that Asgard archaea have a complex actin-based cytoskeleton, providing the first direct visual evidence of the archaeal ancestry of eukaryotes.
Fossils
The timing of the origin of eukaryotes is hard to determine; some acritarchs are known from at least 1.65 billion years ago, and a fossil, Grypania, which may be an alga, is as much as 2.1 billion years old. The "problematic" fossil Diskagma has been found in paleosols 2.2 billion years old.
Reconstruction of the problematic Diskagma buttonii, a terrestrial fossil less than 1mm high, from rocks 2.2 billion years old
Structures proposed to represent "large colonial organisms" have been found in the black shales of the Palaeoproterozoic such as the Francevillian B Formation, in Gabon, dubbed the "Francevillian biota" which is dated at 2.1 billion years old. However, the status of these structures as fossils is contested, with other authors suggesting that they might represent pseudofossils.
The oldest fossils than can unambiguously be assigned to eukaryotes are
from the Ruyang Group of China, dating to approximately 1.8-1.6 billion
years ago. Fossils that are clearly related to modern groups start appearing an estimated 1.2 billion years ago, in the form of red algae, though recent work suggests the existence of fossilized filamentous algae in the Vindhya basin dating back perhaps to 1.6 to 1.7 billion years ago.
The presence of steranes, eukaryotic-specific biomarkers, in Australianshales previously indicated that eukaryotes were present in these rocks dated at 2.7 billion years old, but these Archaean biomarkers have been rebutted as later contaminants. The oldest valid biomarker records are only around 800 million years old. In contrast, a molecular clock analysis suggests the emergence of sterol biosynthesis as early as 2.3 billion years ago. The nature of steranes as eukaryotic biomarkers is further complicated by the production of sterols by some bacteria.
Whenever their origins, eukaryotes may not have become ecologically dominant until much later; a massive increase in the zinc composition of marine sediments 800 million years ago has been attributed to the rise of substantial populations of eukaryotes, which preferentially consume and incorporate zinc relative to prokaryotes, approximately a billion years after their origin (at the latest).
A cotton ball. Cotton is a significant cash crop. According to the National Cotton Council of America, in 2014, China was the world's largest cotton-producing country with an estimated output of about one hundred million 480-pound bales.
A cash crop, also called profit crop, is an agriculturalcrop which is grown to sell for profit. It is typically purchased by parties separate from a farm. The term is used to differentiate marketed crops from staple crop ("subsistence crop") in subsistence agriculture, which are those fed to the producer's own livestock or grown as food for the producer's family.
In earlier times, cash crops were usually only a small (but vital) part of a farm's total yield, while today, especially in developed countries and among smallholders almost all crops are mainly grown for revenue. In the least developed countries, cash crops are usually crops which attract demand in more developed nations, and hence have some export value.
Prices for major cash crops are set in international trade markets with global scope, with some local variation (termed as "basis") based on freight costs and local supply and demand
balance. A consequence of this is that a nation, region, or individual
producer relying on such a crop may suffer low prices should a bumper crop elsewhere lead to excess supply on the global markets. This system has been criticized by traditional farmers. Coffee is an example of a product that has been susceptible to significant commodity futures price variations.
Globalization
Issues involving subsidies and trade barriers on such crops have become controversial in discussions of globalization. Many developing countries take the position that the current international trade system is unfair because it has caused tariffs to be lowered in industrial goods while allowing for low tariffs and agricultural subsidies for agricultural goods.
This makes it difficult for a developing nation to export its goods
overseas, and forces developing nations to compete with imported goods
which are exported from developed nations at artificially low prices.
The practice of exporting at artificially low prices is known as dumping, and is illegal in most nations. Controversy over this issue led to the collapse of the Cancún trade talks in 2003, when the Group of 22 refused to consider agenda items proposed by the European Union unless the issue of agricultural subsidies was addressed.
Per climate zones
Arctic
The Arctic climate is generally not conducive for the cultivation of cash crops. However, one potential cash crop for the Arctic is Rhodiola rosea, a hardy plant used as a medicinal herb that grows in the Arctic. There is currently consumer demand for the plant, but the available supply is less than the demand (as of 2011).
In regions with a tropical climate, coffee, cocoa, sugar cane, bananas, oranges, cotton and jute are common cash crops. The oil palm is a tropical palm tree, and the fruit from it is used to make palm oil. The impact of climate change on the ranges of pests and diseases –
especially those of coffee, cocoa, and banana – is commonly
underestimated. Limiting temperature rise to 1.5 °C (2.7 °F) is vital to
maintaining productivity in the tropics.
Around 60 percent of African workers are employed in the agricultural sector, with about three-fifths of African farmers being subsistence farmers. For example, in Burkina Faso
85% of its residents (over two million people) are reliant upon cotton
production for income, and over half of the country's population lives
in poverty. Larger farms tend to grow cash crops such as coffee, tea, cotton, cocoa, fruit and rubber.
These farms, typically operated by large corporations, cover dozens of
square kilometres and employ large numbers of laborers. Subsistence
farms provide a source of food and a relatively small income for
families, but generally fail to produce enough to make re-investment
possible.
The situation in which African nations export crops while a
significant number of people on the continent struggle with hunger has
been blamed on developed countries, including the United States, Japan and the European Union. These countries protect their own agricultural sectors, through high import tariffs and offer subsidies to their farmers, which some have contended is leading to the overproduction of commodities such as cotton, grain and milk.
The result of this is that the global price of such products is
continually reduced until Africans are unable to compete in world
markets, except in cash crops that do not grow easily in temperate climates.
Africa has realized significant growth in biofuelplantations, many of which are on lands which were purchased by British companies. Jatropha curcas is a cash crop grown for biofuel production in Africa.
Some have criticized the practice of raising non-food plants for export
while Africa has problems with hunger and food shortages, and some
studies have correlated the proliferation of land acquisitions, often
for use to grow non-food cash crops with increasing hunger rates in
Africa.
Australia
Australia produces significant amounts of lentils.It was estimated in 2010 that Australia would produce approximately 143,000 tons of lentils. Most of Australia's lentil harvest is exported to the Indian subcontinent and the Middle East.
Italy
Italy's Cassa per il Mezzogiorno in 1950 led to the government implementing incentives to grow cash crops such as tomatoes, tobacco
and citrus fruits. As a result, they created an over abundance of these
crops causing an over saturation of these crops on the global market.
This caused these crops to depreciate.
Cash cropping in the United States rose to prominence after the baby boomer
generation and the end of World War II. It was seen as a way to feed
the large population boom and continues to be the main factor in having
an affordable food supply in the United States. According to the 1997
U.S. Census of Agriculture, 90% of the farms in the United States are
still owned by families, with an additional 6% owned by a partnership. Cash crop farmers have utilized precision agricultural technologies combined with time-tested practices to produce affordable food. Based upon United States Department of Agriculture (USDA) statistics for 2010, states with the highest fruit production quantities are California, Florida and Washington.
Various potato cultivarsSliced sugarcane, a significant cash crop in Hawaii
Coconut palms are cultivated in more than 80 countries of the world, with a total production of 61 million tonnes per year. The oil and milk derived from it are commonly used in cooking and frying; coconut oil is also widely used in soaps and cosmetics.
Sustainability of cash crops
Approximately 70% of the world's food is produced by 500 million smallholder farmers.
For their livelihood they depend on the production of cash crops, basic
commodities that are hard to differentiate in the market. The great
majority (80%) of the world's farms measure 2 hectares or less.
These smallholder farmers are mainly found in developing countries and
are often unorganized, illiterate or have only basic education.
Smallholder farmers have little bargaining power and incomes are low,
leading to a situation in which they cannot invest much in upscaling
their businesses. In general, farmers lack access to agricultural inputs
and finance, and do not have enough knowledge on good agricultural and
business practices. These high level problems are in many cases
threatening the future of agricultural sectors and theories start
evolving on how to secure a sustainable future for agriculture.
Sustainable market transformations are initiated in which industry
leaders work together in a pre-competitive environment to change market
conditions. Sustainable intensification focuses on facilitating
entrepreneurial farmers. To stimulate farm investment, projects on
access to finance for agriculture are also popping up. One example is
the SCOPE methodology,
an assessment tool that measures the management maturity and
professionalism of producer organizations as to give financing
organizations better insights in the risks involved in financing.
Currently, agricultural finance is always considered risky and avoided
by financial institutions.
Black market cash crops
In the U.S., Cannabis has been termed as a cash crop.
Coca, opium poppies and cannabis are significant black market
cash crops, the prevalence of which varies. In the United States,
cannabis is considered by some to be the most valuable cash crop. In 2006, it was reported in a study by Jon Gettman,
a marijuana policy researcher, that in contrast to government figures
for legal crops such as corn and wheat and using the study's projections
for U.S. cannabis production at that time, cannabis was cited as "the
top cash crop in 12 states and among the top three cash crops in 30".
The study also estimated cannabis production at the time (in 2006) to
be valued at US$35.8 billion, which exceeded the combined value of corn
at $23.3 billion and wheat at $7.5 billion.
The United States is the largest grower of commercial crops that have been genetically engineered in the world, but not without domestic and international opposition.
In
this case, the plaintiff argued both for mandatory labeling on the
basis of consumer demand, and that GMO foods should undergo the same
testing requirements as food additives because they are "materially
changed" and have potentially unidentified health risks. The plaintiff
also alleged that the FDA did not follow the Administrative Procedures Act
in formulating and disseminating its policy on GMO's. The federal
district court rejected all of those arguments and found that the FDA's
determination that GMO's are Generally Recognized as Safe
was neither arbitrary nor capricious. The court gave deference to the
FDA's process on all issues, leaving future plaintiffs little legal
recourse to challenge the FDA's policy on GMO's. Alliance for Bio-Integrity v Shalala, 116 F.Supp.2d 166 (D.D.C. 2000).
Diamond v. Chakrabarty, 447 U.S. 303 (1980), was a United States Supreme Court case dealing with whether genetically modified organisms can be patented.
The Court held that a living, man-made micro-organism is patentable
subject matter as a "manufacture" or "composition of matter" within the
meaning of the Patent Act of 1952. The fact that the organism sought to be patented is alive is no bar to patentability.
Numerous
organizations based in the U.S. oppose or have concerns about genetic
engineering for various reasons. Groups such as the Center for Food Safety, the nonprofit science advocacy group Union of Concerned Scientists, Greenpeace and the World Wildlife Fund have expressed concerns about the FDA's lack of a requirement for additional testing for GMO's, lack of required labeling and the presumption that GMO's are "Generally Recognized as Safe" (GRAS). Some of these groups have questioned whether the FDA is too close to companies that seek approval for their products.
Health concerns
Although
there have been no recorded instances of harm to human health due to
the consumption of genetically engineered foods, there is concern over
their impact on health. One of the largest food recalls in US history,
was the Taco Bell GMO recall, where a Bt corn plant
not approved for human consumption due its risk as an allergen, had
contaminated food products like the tacos at Taco Bell, and a huge
percentage of US's seed supply. No health problems were linked to
Starlink corn, and subsequent evaluations of the Bt trait determined that there is medium risk to human health.
The USA is the largest commercial grower of genetically modified crops in the world. United States regulatory policy is governed by the Coordinated Framework for Regulation of Biotechnology. The United States is not a signatory to the Cartagena Protocol on Biosafety.
For a genetically modified organism to be approved for release it is
assessed by the USDA, the FDA and the EPA. USDA evaluates the plant's
potential to become weeds, the FDA reviews plants that could enter or
alter the food supply and the EPA regulates the genetically modified
plants with pesticide properties. Most developed genetically modified
plants are reviewed by at least two of the agencies, with many subject
to all three. Final approval can still be denied by individual counties within each state. In 2004, Mendocino County,
California became the first and only county to impose a ban on the
"Propagation, Cultivation, Raising, and Growing of Genetically Modified
Organisms", the measure passing with a 57% majority. (See Mendocino County GMO Ban)
U.S. Department of Agriculture
The Biotechnology Regulatory Services program of the Animal and Plant Health Inspection Service (APHIS) agency within the USDA is concerned with protecting agriculture and the environment from potential pests under the Plant Protection Act of 2000 (part of the Agriculture Risk Protection Act) and the National Environmental Policy Act (NEPA). Each transgenic event is regulated separately as the transgene insertion locus varies even when using identical constructs and host genotypes. This could result in different expression patterns or could affect the function of other endogenous genes within the host. The USDA is responsible for approving field trials of GM plants under either the notification or permit procedures.
The notification procedure is a streamlined process for the simplest or
most familiar genetically engineered plants that meet six criteria (is
not a noxious weed,
the function of the genetic material is known and characterized, stable
integration, no significant risk of creating new viruses and that no
animal or human pathogen sequences are present). Most field trials are approved under the notification procedure.
The permit procedure is much more elaborate and is required for all
genetically engineered organisms that do not meet the notification
requirements or any plant-made pharmaceuticals or plant-made industrial products.
APHIS officials are responsible for inspecting the field trials.
At least one inspection is carried out for each state listed on a
permit, while inspection of field trials authorized by notification is
conducted based on the relative risk of each trial.
For field trials of organisms that contain pharmaceutical or industrial
compounds, inspections are carried out more frequently (five times
during establishment and twice yearly after that). If the inspectors are
satisfied that there are no regulatory concerns they issue a Notice of
Compliance. If the regulations are not being adhered to the inspectors
will issue a Notice of Non-Compliance requesting that the deviations be
fixed, or for more serious breaches a warning letter requiring a written
response and corrective action to be taken within a given time frame.
Formal investigations are carried out on developers who may not be
adhering to regulations, permit conditions, or other requirements, which
can result in civil penalties or criminal charges.
In 1993, the USDA proposal to remove regulatory oversight from GM organisms deemed environmentally benign was approved and four GM plants (Flavr Savr tomato, virus-resistant squash, bromoxynil-tolerant cotton and glyphosate-tolerant soybean) obtained non-regulatory status that year.
Non-regulated status means that permits and notifications are no longer
required for introductions of this organism. Applicants can petition
APHIS for non-regulated status if the GM organism poses no more of a
plant pest risk than an equivalent non-GM organism. APHIS will prepare at least two documents (an Environmental Assessment and a determination of non-regulatory status) under the NEPA while considering the application.
Four federal district courtsuits have been brought against APHIS challenging their regulation of GM plants. Two involved field trials (herbicide-tolerant turfgrass in Oregon; pharmaceutical-producing corn and sugar in Hawaii) and the other two were the deregulation of GM alfalfa and GM Sugar Beet.
APHIS initially lost all four cases, with the judges ruling they failed
to diligently follow the NEPA guidelines. However, the Supreme Court
overturned the nationwide ban on GM alfalfa and an appeal court allowed the partial deregulation of GM sugar beet crops. After APHIS prepared Environmental Impact Statements for both crops they were deregulated again.
Food and Drug Administration
The FDA
is responsible for the safety and security of human and animal food and
drugs, including any that are genetically modified. The FDA was
responsible for approving the first commercialized GMO, Genetech's
genetically modified human insulin (Humulin) in 1982 and the first commercialized GM whole food, Calgene's Flavr Savr tomato in 1994. When evaluating new GM foods or feed the FDA looks for the presence of any new or altered allergens and toxicants and examines changes in the levels of nutritional and anti-nutritional substances. Food and feed that is identical or nearly identical in composition to current products is deemed to be substantially equivalent and is not required to undergo review by the FDA.
The FDA has been criticized for using substantial equivalence, with a
major accusation being that FDA review is essentially voluntary as
almost all GM products are substantially equivalent. However, all GM food and feed currently on the US market (as of 2008) have undergone a FDA consultation, where the developer submits the compositional data and FDA scientist compare it to regular food and feed.
The FDA consultation focuses on whether the new food or feed
contains any new allergens or toxic substances and whether the
nutritional components of the food or feed have increased or decreased.
The developer submits documentation to the FDA describing the food or
feed and a FDA assigned caseworker can then request additional
information on expected dietary exposure, in particular if any risk
groups (children, elderly etc.) might be exposed. As of 2007, the FDA
has not identified any genetically modified foods with unexpected
changes in the nutrient composition or levels of allergens or toxic
substances. However, allergic proteins have been detected when some GM products have undergone testing. Pioneer Hi-Bred inserted a gene from the Brazil nut into transgenic soybean resulting in soy with an enhanced nutritional profile. The inserted gene did not translate into a known allergen at the time, but when tested with serum from people who are allergic to Brazil nut the allergenic nature of the protein was discovered.
The development of the transgenic soybean expressing a Brazil nut
allergen was stopped after these tests. The FDA consultation process is
relatively (when compared to the other agencies regulating GM) informal
and they do not approve new GM products. Instead they issue a memo stating whether the new food is the same as or different from the non-modified variety.
The Center for Veterinary Medicine of the FDA regulates genetically modified animals in consultation with Centers at the FDA responsible for regulating pharmaceuticals or other medical products derived from biopharm animals. The FDA also has extra guidelines that apply to genetically modified animals that will be used in the manufacturing and testing of therapeutic products and xenotransplantation.
The FDA guidance documents do not establish legally binding laws and
are viewed as recommendations, unless specific regulatory or statutory
requirements are cited. Any relevant federal, State, or local laws and
regulations must also be adhered to.
Environmental Protection Agency
The EPA regulates substances with pesticide characteristics, looking at potential threats to human health or the environment.
They claim not to regulate the genetically modified plants, but the
pesticides produced by the plants or properties that change the usage of
applied pesticides . This includes; plants engineered to produce
resistance to herbicides (e.g. Roundup Ready), plants that produce their own pesticides (e.g. BT)
and virus resistant plants. Authority to regulate the pesticide
properties in genetically modified organisms was granted in the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and the Federal Food, Drug, and Cosmetic Act
(FFDCA). The EPA published regulations in 1994 and begun acting on them
in 1995. In 1994 they proposed the exemption of three categories of
genetically modified plants under their regulation. These were plants
where the genetic material originated in sexually compatible plants (cisgenic), plants that used physical barriers to prevent the target pest from attaching itself, and plants expressing viral coat proteins to protect against virus infection.
In 2001, rules regarding exemption of cisgenic plants had been
finalised. The other two proposed exemptions were still under review in
2010.
The EPA evaluated each submission on a case-by-case basis. The
EPA assesses data concerning the characterisation of the end-product of
the engineered organism (presently all plants evaluated produce
proteins), as well as data on mammalian toxicity, effects on non-target
organisms and environmental metabolism.
For Bt products the producer must also supply an insect resistance
management program. For herbicide resistant plants the EPA co-ordinates
with the USDA and FDA, but does not regulate the plant itself. Instead
it regulates the herbicide and its use on the new cultivar. The EPA examines the construct
used to transform the plant and the biology of recipient plant. The
sequence of the resulting protein must be described, expression pattern
and intencity verified and any modifications to the protein reported.
The EPA considers the potential allergenicity of the product, issues
surrounding gene flow into wild species, possible effects on non-target
organisms, likelihood of it persisting in the environment and the
potential for insect resistance developing when assessing submissions.
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