here’s a small smattering of examples of human biodiversity. a REALLY small smattering! just a handful of examples that i’ve thought of off the top of my head. i’ll keep adding to this list. feel free to help me out by leaving more examples in the comments! thanks. (^_^)
• eye color. people have different colored eyes, especially people of european descent. many genes are involved in eye color — not all of them are known yet.
• hair color. people have different colored hair, again especially people of european descent. and, again, we still don’t know all of the genes involved. yet.
• skin color. lots of different colors, obviously. still working out the genetics there, too.
• EDAR. a gene connected to embryonic development. from wikipedia: “A point mutation in EDAR, 370A, found in most East Asians but not common in African or European populations, is thought to be responsible for a number of differences between these populations, including the thicker hair, more numerous sweat glands, smaller breasts, and dentition characteristic of East Asians. The difference in dentition was not visible in mice due to the radically different structure of mice from human teeth, but it is considered reasonable that that difference also is due to the mutation. The 370A mutation arose in humans approximately 30,000 years ago, and now is found in 93% of Han Chinese and in the majority of people in nearby Asian populations.”
• sickle-cell trait. an adaptation giving a survival advantage in malarial regions, found especially in subsaharan africa, but unfortunately resulting in sickle-cell disease in some individuals. see here re. the genetics.
• lactase persistence. means you can have a starbucks latte without having to order soy milk. (~_^) from wikipedia: “Joel Hirschhorn of Harvard Medical School discovered that lactase persistence was due to the presence of a haplotype composed of more than 1 million nucleotide base pairs, including the lactase gene. The presence of this gene is the cause of lactase persistence. Today, this haplotype can be found in 80% of Europeans and Americans of European ancestry. On the other hand, the percentage of the population who are lactase persistent in sub-Saharan Africa and Southeast Asia is very low. It is absent in the Bantu of South Africa and most Chinese populations. These geographical distributions strongly correlate with the spread of domesticated cattle. About 5,000 to 10,000 years ago, this haplotype came under very strong selective pressure. This period matches the rise of dairy farming. As dairy farming originated in Europe, Europeans were exposed to increased lactose nutrition provided by dairy products, resulting in positive natural selection. The additional nutrition provided by the dairy was very important for survival in the recent history of Europe; therefore the supply of fresh milk leads to the favoring of the lactase persistent trait. As dairy farming spread across the globe, after the separation of Europe-derived populations from Asian- and African-derived populations, and after the colonization of Europe, the strong positive selection occurred in a large region, leading to the global spread of lactase persistence.” — there’re also a couple of other populations with lactase persistence stemming from different mutations.
• high-altitude adapation. there are different adapations in different populations, notably among the tibetans, the andeans, and the ethiopian highlanders. the tibetan adaptations seem to work the best, prolly because some of what they’ve got is really old.
• cold adaptations. in certain alleles in siberians. (i wish i had these!)
• height in pgymies. different subsaharan african pygmy populations show different height adaptations.
• ASPM. a gene connected to brain development. from wikipedia: “A new allele (version) of ASPM appeared sometime between 14,100 and 500 years ago with a mean estimate of 5,800 years ago. The new allele has a frequency of about 50% in populations of the Middle East and Europe, it is less frequent in East Asia, and has low frequencies among Sub-Saharan African populations. It is also found with an unusually high percentage among the people of Papua New Guinea, with a 59.4% occurrence.”
• microcephalin (MCPH1). another gene connected to brain development. from wikipedia: “A derived form of MCPH1 called haplogroup D appeared about 37,000 years ago (any time between 14,000 and 60,000 years ago) and has spread to become the most common form of microcephalin throughout the world except Sub-Saharan Africa; this rapid spread suggests a selective sweep. However, scientists have not identified the evolutionary pressures that may have caused the spread of these mutations. This variant of the gene is thought to contribute to increased brain volume. Modern distributions of chromosomes bearing the ancestral forms of MCPH1 and ASPM are correlated with the incidence of tonal languages, but the nature of this relationship is far from clear. Haplogroup D may have originated from a lineage separated from modern humans approximately 1.1 million years ago and later introgressed into humans. This finding supports the possibility of admixture between modern humans and extinct Homo spp. While Neanderthals have been suggested as the possible source of this haplotype, the haplotype was not found in the individuals used to prepare the first draft of the Neanderthal genome.”
this is one of a set of posts on What is Human Biodiversity? please, before you
fire off a rant leave a comment here, check out the other posts, because your question or objection may have been dealt with in one of them. here they all are!:
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