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Drifty Gene Hypothesis
The "drifty gene hypothesis" was proposed by the British biologist John Speakman as an alternative to the thrifty gene hypothesis originally proposed by James V Neel in 1962. Speakman's critique of the thrifty gene hypothesis is based on an analysis of the pattern and level of mortality during famines. Despite much anecdotal evidence used to suggest that famines cause substantial mortality, Speakman suggests that where real data are available famines actually involve rather low levels of mortality and there is no evidence that fat people survive famines better than lean people. In fact, mortality actually falls mostly on groups such as the very young and very old where differential mortality in relation to body composition is highly unlikely. Moreover, there is some confusion among proponents of the thrifty gene hypothesis about how long famines have played a role in evolution. On the one hand some proponents suggest famines have been an "ever present" threat dating back to the da ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Speakman
John Roger Speakman (born 1958) is a British biologist working at the University of Aberdeen, Institute of Biological and Environmental Sciences, for which he was Director from 2007 to 2011. He leads the University's Energetics Research Group, which uses doubly labeled water (DLW) to investigate energy expenditure and balance in animals. One or more of the preceding sentences incorporates text from the royalsociety.org website where: Between 2011-2020, he was a '1000 talents' Professor at the Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, in Beijing, China, where he ran the molecular energetics group. In 2020 he moved to the Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences in Shenzhen, China where he works at the Center for Energy Metabolism and Reproduction and Head of the Shenzhen Key laboratory of Metabolic Health. Education Speakman was educated at Leigh Grammar School, near Manchester, and then went to the Univer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thrifty Gene Hypothesis
The thrifty gene hypothesis is an attempt by geneticist James V. Neel to explain why certain populations and subpopulations in the modern day are prone to diabetes mellitus type 2. He proposed the hypothesis in 1962 to resolve a problem: diabetes is a harmful medical condition, yet it is also common, and has a strong genetic basis. The problem is to understand how disease with a likely genetic component and with such negative effects may have been favoured by the process of natural selection. Neel suggested the resolution to this problem is that genes which predispose to diabetes (called 'thrifty genes') were historically advantageous, but they became detrimental in the modern world. In his words they were "rendered detrimental by 'progress'". Neel's primary interest was in diabetes, but the idea was soon expanded to encompass obesity as well. Thrifty genes are genes which enable individuals to efficiently collect and process food to deposit fat during periods of food abundance in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Famine
A famine is a widespread scarcity of food caused by several possible factors, including, but not limited to war, natural disasters, crop failure, widespread poverty, an Financial crisis, economic catastrophe or government policies. This phenomenon is usually accompanied or followed by regional malnutrition, starvation, epidemic, and increased death, mortality. Every inhabited continent in the world has experienced a period of famine throughout history. During the 19th and 20th centuries, Southeast Asia, Southeast and South Asia, as well as Eastern Europe, Eastern and Central Europe, suffered the greatest number of fatalities due to famine. Deaths caused by famine declined sharply beginning in the 1970s, with numbers falling further since 2000. Since 2010, Africa has been the most affected continent in the world by famine. As of 2025, Haiti and Afghanistan are the two states with the most catastrophic and widespread states of famine, followed by Palestine (confined to Gaza Strip ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Australopithecine
The australopithecines (), formally Australopithecina or Hominina, are generally any species in the related genera of ''Australopithecus'' and ''Paranthropus''. It may also include members of '' Kenyanthropus'', ''Ardipithecus'', and '' Praeanthropus''. The term comes from a former classification as members of a distinct subfamily, the Australopithecinae. They are classified within the Australopithecina subtribe of the Hominini tribe. These related species are sometimes collectively termed australopithecines, australopiths, or homininians. They are the extinct, close relatives of modern humans and, together with the extant genus ''Homo'', comprise the human clade. There is no general agreement to whether australopithecines are closest relatives of modern humans, as it has been argued that they are more closely related to extant African apes. Members of the human clade, i.e. the Hominini after the split from the chimpanzees, are called Hominina (''see Hominidae; terms "hominids" ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
History Of Agriculture
Agriculture began independently in different parts of the globe, and included a diverse range of Taxon, taxa. At least eleven separate regions of the Old World, Old and New World were involved as independent centers of origin. The development of agriculture about 12,000 years ago changed the way humans lived. They switched from nomadic hunter-gatherer lifestyles to permanent settlements and farming. Wild cereal, grains were collected and eaten from at least 104,000 years ago. However, domestication did not occur until much later. The earliest evidence of small-scale cultivation of edible grasses is from around 21,000 BC with the Ohalo II people on the shores of the Sea of Galilee. By around 9500 BC, the eight Neolithic founder crops – emmer wheat, einkorn wheat, barley, hulled barley, peas, lentils, Vicia ervilia, bitter vetch, chickpeas, and flax – were cultivated in the Levant. Rye may have been cultivated earlier, but this claim remains controversial. Re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genetic Drift
Genetic drift, also known as random genetic drift, allelic drift or the Wright effect, is the change in the Allele frequency, frequency of an existing gene variant (allele) in a population due to random chance. Genetic drift may cause gene variants to disappear completely and thereby reduce genetic variation. It can also cause initially rare alleles to become much more frequent and even fixed. When few copies of an allele exist, the effect of genetic drift is more notable, and when many copies exist, the effect is less notable (due to the law of large numbers). In the middle of the 20th century, vigorous debates occurred over the relative importance of natural selection versus neutral processes, including genetic drift. Ronald Fisher, who explained natural selection using Mendelian inheritance, Mendelian genetics, held the view that genetic drift plays at most a minor role in evolution, and this remained the dominant view for several decades. In 1968, population geneticist Mot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Predation
Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common List of feeding behaviours, feeding behaviours that includes parasitism and micropredation (which usually do not kill the Host (biology), host) and parasitoidism (which always does, eventually). It is distinct from Scavenger, scavenging on dead prey, though many predators also scavenge; it overlaps with Herbivore, herbivory, as Seed predation, seed predators and destructive frugivores are predators. Predation behavior varies significantly depending on the organism. Many predators, especially carnivores, have evolved distinct hunting strategy, hunting strategies. Pursuit predation involves the active search for and pursuit of prey, whilst ambush predation, ambush predators instead wait for prey to present an opportunity for capture, and often use stealth or aggressive mimicry. Other predators are opportunism, opportunistic or om ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genetics Of Obesity
Like many other medical conditions, obesity is the result of an interplay between environmental and genetic factors. Studies have identified variants in several genes that may contribute to weight gain and body fat distribution, although only in a few cases are genes the primary cause of obesity. Recent research indicates that environmental influences can lead to epigenetic modifications affecting gene expression related to obesity. These changes can alter metabolic processes and appetite regulation, contributing to obesity development. Polymorphisms in various genes controlling appetite and metabolism predispose to obesity under certain dietary conditions. The percentage of obesity that can be attributed to genetics varies widely, depending on the population examined, from 6% to 85%, with the typical estimate at 50%. Twin studies have consistently shown that genetics account for 40% to 70% of the variation in body mass index (BMI) across individuals (Loos & Yeo, 2022). It is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
New World Syndrome
New World syndrome is a set of non-communicable diseases brought on by consumption of junk food and a sedentary lifestyle, especially common to indigenous peoples of the Americas, Oceania, and circumpolar peoples. It is characterized by obesity, heart disease, diabetes, hypertension, and shortened life span. Causes New World syndrome is linked to a change from a traditional diet and exercise to a Western diet and a sedentary lifestyle. Traditional occupations of indigenous people—such as fishing, farming, and hunting—tended to involve constant activity, whereas modern office jobs do not. The introduction of modern transportation such as automobiles also decreased physical exertion. Meanwhile, Western foods which are rich in fat, salt, sugar, and refined starches are also imported into countries. The amount of carbohydrates in diets increases. Diagnosis The diagnosis does not require specific criteria. Obesity is often followed by its complications like hyperlipidemia, hyperte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
