Archives for posts with tag: biology 101

there were a handful of science news stories out this past week about how a couple of researchers reportedly discovered a case of “group selection” in certain spiders (Anelosimus studiosus or tangle web spiders): for example, see Proving ‘group selection': Spider colonies need the correct mix of personalities to survive and Elusive Form of Evolution Seen in Spiders. a bunch of people on twitter got all excited about this finding, because they wonder if (some of them i think hope that) group selection might also apply to groups of humans. i agree: that would be very interesting to know one way or the other. so i went and read the original paper — Site-specific group selection drives locally adapted group compositions — to see what these guys had found.

before i offer up my admittedly layman’s thoughts on this paper, let me first say what a really neat piece of research this was! if there existed a nobel prize for geeky dedication and sheer nerdiness, these guys would’ve won it! — and i mean that as a compliment! the researchers, pruitt and goodnight, studied groups of tangle web spiders in the wild, captured some and brought them back to their lab, conducted personality tests on the spiders (yes! there are apparently personality tests for spiders!), painstakingly painted those little dots on the backs of individuals to keep track of them (you know, like how they sometimes do with bees), bred the spiders, released new groups of them back into the wild, and checked up on them one and two generations later to see how they fared. this is some really cool research! nerds ftw! (^_^)

but did they find evidence for group selection?

weeeellll, no, i don’t think so.

to begin with, right at the start of the paper pruitt and goodnight (p&g) define group selection as “selection caused by the differential extinction or proliferation of groups.” eeeehhhh, as far as i understand it, that’s not really the definition of group selection, and even the authors admit that their definition is a “broad” one.

group selection is more accurately defined as when “natural selection [operates] between groups of organisms, rather than between individuals.” in contrast, p&g’s broad definition could theoretically include cases in which natural selection worked between individuals (individual selection) which also just incidentally happened to result in the proliferation of the group to which the lucky selected individuals belonged. an example of this is the selection for lactase persistence in some humans in which those individuals who could drink milk as adults were able to leave behind more descendants than those individuals who could not. while lactase persistence might indeed have benefitted groups of milk-drinking individuals, natural selection did not act on the group, but rather on the individuals in that group. (pretty sure i stole this example from @supermisdreavus, but i can’t find where he said that right now.)

in other words, you always need to work out what the target of selection is: the group or the individuals that make up the group. (really it’s ultimately the genes, but — oh, nevermind.) remember that “‘a fleet herd of deer’ is really just a herd of fleet deer.”

so, really, the discussion could end right here, because i don’t think the authors are talking about group selection proper. but, since i’ve read the whole paper, i’ll carry on. (yes, i’m one of those people who’s never learned to quit while they’re ahead!)

a. studiosus spiders live either as solitary individuals or in groups where they cooperate on tasks like hunting and the raising of young. the individuals that live together in groups are, on average, more closely related to one another than those that live alone [pdf] — they’re generally as related to one another as though they were half-siblings. one reason why they’re probably not more related to one another in these groups — like to the degree that ants or bees in colonies often are — is that the males move between groups. remember that.

the personality types of the individual spiders in a. studiosus groups come in two sorts: docile and aggressive. the docile spiders are typically pretty laid back and aren’t much bothered by the presence of other spiders (even spiders from other species), whereas the aggressive individuals like their space — they’ll chase off other individuals. individuals of both types are found in groups of a. studiosus, but the frequencies vary. from the paper:

“At…high-resource sites, small colonies were dominated by docile females and the frequency of aggressive individuals increased with colony size. By contrast, at low-resources sites, small colonies were dominated by the aggressive phenotype and the frequency of the docile phenotype increased with colony size.”

well, that doesn’t sound too surprising at all. in locales where there is plenty of resources, there are more laid back individuals in the colonies, prolly ’cause being laid back works just fine. in areas where resources are lacking, more aggressive individuals do better. btw, they found that the heritability of these personality types in the spiders is 0.66.

groups that have more docile individuals (i.e. the ones in high-resource areas) are at a greater risk of invasion by other types of spiders which, over the long-term, tends to be a really bad thing for an a. studiosus colony (i.e. it’s usually destroyed). groups that have more aggressive individuals (i.e. the ones in low-resource areas) tend in bad times to experience too much “egg case cannibalism.” needless to say, that’s not a good thing over the long-term either.

what p&g did in their study was to introduce into the wild — into differing environments — groups having varying frequencies of these personality types [source]:

“He [pruitt] took spiders from warrior-heavy colonies and used them to assemble new groups that were heavy on the nannies. He also used spiders from mostly docile colonies to create warrior-laden groups. In addition, he assembled control groups that matched the composition of their original groups.”

what they found was that after three generations:

“60 percent of the colonies were extinct. Control groups that returned to their ancestral homes tended to do well, and those that were transplanted into a new environment generally died. Neither of these outcomes was much of a surprise.

The most interesting results came from colonies made up of spiders that had been forced into a composition different from the one they grew up in — warrior-majority colonies containing spiders from mostly docile groups, for example. The colonies whose composition fit the new environment tended to survive. But over time, surviving colonies reverted to their members’ original group composition. The warrior-majority colonies went back to having more nannies, for example. On the face of it, this is bizarre behavior; if the colonies are well-suited to their environment, why not maintain that ratio? It seems that some innate sense, perhaps encoded in the spiders’ genes, pulled the colony back to its original configuration, even though this change meant the colony would perish.”

well, i dunno. is that really “bizarre behavior?” i mean, if the personality types of a. studiosus are really highly heritable (0.66), is it strange that a population having come from a bunch of docile individuals should regress toward a docile mean? and vice versa? don’t forget, too, that the individuals in these groups are all related to one another as though they were half-siblings, so presumably individuals of either personality type might carry a great many genes of the other type in their genomes. (don’t know about that — i’m just guessing here, tbh.)

what really made me question whether or not this is “bizarre behavior” is the way in which the researchers bred the spiders when they had them in captivity [from the methods section at the end of the paper]:

“Females were mated randomly to a male of like behaviour type from their same source population, but which was collected from a source colony >5m distance.”

hmmmm. i dunno about that. they mated all the females with males of the same personality types, docile or aggressive? i’m guessing that they did this in order to reduce the number of possible confounding factors in the study, but i’m afraid they might’ve added something to the mix here that wouldn’t be found in nature, i.e. a 100% assortative mating rate (for personality type). mightn’t this almost guarantee that individual spider lineages would regress to their original personality-type means? docile females always mated with docile males and aggressive females always mated with aggressive males? that seems unlikely to happen in nature, especially given the fact that the males normally leave their colonies and move to others. (btw, male a. studiosus spiders prefer moving into colonies over mating with lone females. typical males, favoring harems! (~_^) )

p&g offer a number of explanations for how the frequencies of personalities in the groups might change over time:

“How native spiders are actually able to adjust their composition is unknown, but plausible regulatory mechanisms include developmental plasticity in the docile:aggressive phenotypes, policing of group membership, phenotype-biased dispersal, and/or selective cessation of reproduction.”

they reject the first explanation (the plasticity one) on the basis (in part) of the rather high heritability of spider personality types which they found. i’m inclined to agree with them on that.

out of their other reasons, policing of group membership and selective cessation of reproduction are behaviors that can be easily explained by natural selection between individuals, especially in populations that have rather highly related individuals so that levels of altruism are pretty high. the selective cessation of reproduction occurs, for instance, in some ant colonies since, due to the really high degrees of relatedness between individuals, the inclusive fitness payoffs are really large (eg. if you share three-quarters of your dna with your sister’s offspring, there’ll be a greater genetic payoff in helping her to reproduce rather than reproducing yourself, since you’d only share half of your genome with your offspring). that’s individual selection, not group selection. h*ck! both behaviors also occur in meerkat groups, although they, of course, show much less specialization of individuals than ants or bees. the policing of group membership can also be plausibly explained by natural selection between individuals — for example, aggressive individuals keep at bay all sorts individuals because that’s good for aggressive individuals (who are typically found in sparse environments).

so, i’m not at all convinced that pruitt and goodnight have found an example of group selection. i think they’ve found that genetics (as indicated by the heritability of the spiders’ personality traits) and natural selection certainly shape the average characteristics of groups, but it looks to me as though the seemingly “bizarre behaviors” that they found can easily be explained by individual selection. in fact, i’m more than a little concerned that due to the way they bred the spiders, p&g may have affected the outcomes of the reintroduced groups.

see also: The False Allure of Group Selection from steven pinker.

(note: comments do not require an email. a. studiosus group web!)

so this paper was making the rounds on twitter earlier in the week…

Demonstrating the Validity of Twin Research in Criminology [pdf]

…and everyone was like, “you have GOT to read this!” so i did. and, yeah, it’s really good! i highly recommend having a read of it.

the paper was written as a response to another paper entitled Pulling back the curtain on heritability studies: Biosocial criminology in the postgenomic era.

postgenomic? wt…? what planet do those guys live on?

anyway…Demonstrating the Validity makes many very right and very interesting points including the following:

1) a common assumption in behavioral genetics analyses is that human matings are random (they’re not — there’s a whole lot of assortative mating when humans go forth and multiply) and that assumption can lead to an underestimate of heritability estimates.

2) another assumption — the equal environments assumption (i.e. that both identical and fraternal twins share equal environments as kids) — leads to an overestimate of heritability estimates.

the authors of the paper show, however, that since these two assumptions are often found together in twin studies, that the over- and underestimates wind up more or less balancing each other out (see below — and see the paper!).

(i, of course, couldn’t help thinking that if assortative mating leads to underestimates of heritability, what would lots of inbreeding in a population do? so far, all twins studies have come from w.e.i.r.d. populations, though — afaik — so the inbreeding issue prolly doesn’t matter. but, if you should ever see some heritability estimates coming out of saudi arabia or sicily, heads up!)

other important points from the paper [my emphases in bold]:

When multiple divergent methods converge to illustrate a consistent finding, it is logically reasonable and empirically sound to accept as valid the results of the divergent methods. The primary reason for such a conclusion is the nonoverlapping assumptions underlying the various methods. This dynamic is illustrated in the convergence in findings between classical twin design studies and various molecular genetics methodologies. GCTA and CSG studies are examples of methodologies that are not subject to the same assumptions as classical twin designs and yet provide convergence in terms of the differential influence of genetic and environmental factors on a variety of behavioral phenotypes, including antisocial behavior. In direct contrast to the appraisal provided by Burt and Simons, the most cutting-edge research emanating from molecular genetics relies heavily on the findings of classical twin design studies and is continually providing empirical support for the validity of such studies.”

oh yeah!

also:

“We have shown empirically that violations of the assumptions of behavioral genetics studies do not invalidate heritability estimates. This is not a matter of opinion but a matter of mathematical evidence. Under certain conditions, our calculations and simulations revealed that heritability estimates will be slightly upwardly biased (probably no more than 5–10 percentage points). Under other conditions, heritability estimates will be downwardly biased (probably no more than 5–10 percentage points). Under the most likely condition, where multiple violations occur simultaneously, the biasing influences of assumption violations wash out, with upwardly biasing factors canceling downwardly biasing factors. Moreover, the overall pattern of findings flowing from the 61 studies examining the EEA revealed the same conclusions offered by our calculations and simulation data. Needless to say, no ‘fatal flaw’ in behavioral genetic methodologies or assumptions has been discovered and the conclusion that ‘all of these models are biased toward inflating heritability and underestimating shared environmental influences’ (Burt and Simons, 2014: 226, emphasis in original) is unequivocally incorrect.”

good stuff! read the whole thing here! and don’t miss all the supplementary materials here!

(note: comments do not require an email. identical. almost.)

september 10, 506 — 1,508 years ago today — was the final day of the council of agde, a meeting of bishops from all over what was then the visigothic kingdom in southern france (and spain, too, obviously). the council was headed by caesarius of arles and held at the basilica of st. andrew. (don’t know on which day the council was convened — sometime in late august.) the church is still there, btw!:

agde

an interesting little sidenote is that the visigoths at the time were still arians, so this meeting of bishops really related to, and would’ve affected only, the gallo-roman population of the region. in fact, the bishops were all very much gallo-romans themselves!

anyway, the council issued numerous canons, one of which forbade marriage to first and second cousins. this is the earliest official cousin marriage ban by the church that i know of, although st. augustine of hippo (d.430) certainly discussed at length in his The City of God (early fifth century) how it would be a good thing if christians were to marry out, a theme that st. aquinas would later pick up on.

people often ask me: “so why did the church get it into its head to ban cousin marriage, hbd chick?”

i. don’t. know. (*^_^*)

as i said above, this is the earliest official ban against cousin marriage from church authorities that we know of. what possessed the gallo-roman bishops at agde to do so, i have no idea. bishop caesarius was certainly an interesting fellow though. for instance, he thought that all priests and bishops (and nuns) ought to live austere lives like monks, and he actually instituted that policy in his own disocese, so i suspect that he was one of these guys who really did want to recreate god’s kingdom here on earth as much as possible, and he seems to have practiced what he preached.

caesarius’ teacher was one julianus pomerius, and his teacher was st. augustine, so here we have a direct line from augustine — who thought that christians ought to marry out — to caesarius and his council issuing this marriage canon. the funny thing is, though, augustine’s teacher was st. ambrose (d.397) who also had some things to say about cousin marriage — in fact, it was apparently he who recommended to theodosius i (d.395) to issue a secular ban against cousin marriage in the empire (theodosius did, but it didn’t stick — theodosius ii rescinded the ban). funnily enough, ambrose, like caesarius, was also from gaul (trier), so we come nearly full circle with these connections.

i suspect that the idea of avoiding cousin marriage was somehow a roman idea which was familiar to these early, urbanized, roman (or romanized) church leaders, one which they began to utilize when they encountered all these clannish barbarians (in gaul and in north africa, for example) and, as christopher burd put it on twitter, uncivilized, inbreeding country “hicks” in general. my guess is that they were trying to come up with a way to get rid of all the clannish infighting — and their plan just happened to work MUCH better than they ever imagined.

what i don’t understand — and what i need to find out more about — is how the early medieval church functioned. how the hierarchy worked and how the issuing of rules and regulations happened.

i’ve read a little about this council of agde now, and the historians i’ve read describe it as a “national” council — their scare quotes, not mine — since, unlike one of the huge church councils such as nicaea, the bishops who attended agde were only local — just from the areas in southern france held by the visigoths. what i want to know is, were the canons issued at agde binding everywhere then, or just in southern france there? could bishops in southern italy or ireland or constantinople just say, oh h*ck, we’re not going to follow those silly canons, or were they obliged to? or did canons issued by “national” councils need to be approved by rome first? i have no idea. Further Research is RequiredTM.

if canons issued by local councils only applied locally, that might explain why cousin marriage appears to have continued for some time after 506, like among the franks, for instance, who were just a stone’s throw away in northern france (until they took over the visigothic kingdom!), but who don’t seem to have taken these cousin marriage bans seriously until something like the 700s.

we do know, though, that rome was definitely behind the cousin marriage bans by the late sixth-early seventh centuries. augustine of canterbury (d.604) was sent in 595 to convert the anglo-saxons in england by pope gregory the great. he wrote to pope gregory in a panic asking what he should do about all the cousin marriage among the anglo-saxons, to which gregory replied that the newly converted should be allowed to remain married to their cousins, but going forward, NO cousin marriage.

how and when hq back in rome began backing this idea remains to be discovered.

anyway…happy council of agde day to you all! (^_^)

(note: comments do not require an email. 12th-century reliquary of caesarius of arles.)

pinker, that is. staffan wins, of course! (^_^)

if you haven’t read staffan’s latest post, you really should! it’s terrific!: The Myth of the Expanding Circle or You Can’t Learn How to Be an English Vegetarian.

here’s a short excerpt:

“[Goldstien] argues that it was Enlightenment (aka the Age of Reason), beginning from late 1600s, that expanded the circle of empathy, a process driven by the thinkers of that era,

“‘…if you look at the history of moral progress, you can trace a direct pathway from reasoned arguments to changes in the way that we actually feel. Time and again, a thinker would lay out an argument as to why some practice was indefensible, irrational, inconsistent with values already held.’

“We wouldn’t like to be kept as slaves, we wouldn’t like this for our family or friends either, so why would we like it for foreigners? Reason compels us to widen our circle of empathy.

“She then proceeds to illustrate her point with some humanitarians like Bentham, Erasmus, John Locke, Mary Astell etc. Pinker concedes and they both reflect on how this reason-driven process will make our grandchildren think of us as barbarians given how much further their circle of empathy will reach. End of story.

“And yet at the beginning of the dialogue Pinker stated,

“‘My fellow psychologists have shown that we’re led by our bodies and our emotions and use our puny powers of reason merely to rationalize our gut feelings after the fact.’

“This of course refers to Jonathan Haidt and others whose research makes a good case for such post hoc rationalization being an important aspect of human nature. To illustrate this behavior he likens our emotions with an elephant and our reason with the rider. The elephant, being much stronger, walks about as he pleases while the helpless rider pretends that he is in complete control.

“Given this statement, it’s a bit disconcerting how easily Pinker ignores the obvious risk that their conclusion might also be post hoc rationalization. After all, two top notch academics agreeing that all you need is reason sounds a bit like two hippies agreeing that all you need is love. So is it post hoc? It definitely has some conspicuous flaws that suggest so.

“As Pinker himself pointed out back in 2002 in his book The Blank Slate, all behavioral traits are highly inheritable and change very little over the lifespan and, most importantly, they are unaffected by shared environment, such as schools, education – and humanitarian essays. But width of empathy must, by any reasonable definition, be a behavioral trait. But by their logic it would be a trait like no other, strongly affected by shared environment, even though all other traits, thus including very similar traits like ingroup loyalty and identification, aren’t. So either width of empathy isn’t a behavioral trait – which is crazy – or it is somehow a completely unique trait affected by shared environment. Either way Pinker and Goldstein have some serious splaining to do.”

(~_^) read the whole post @staffan’s — it’s definitely NOT to be missed!

(note: comments do not require an email. The Blank Slate.)

THIS is the best article i’ve read all week! possibly all month. in fact, it’s soooo interesting, i’m going to read it over and over again! (pretty sure i’ve got it memorized already actually…. (*^_^*) )

by ed west, The Church v the Family appeared in The Catholic Herald a couple of weeks ago:

“So why is Europe different? The answer is the Catholic Church. Christianity in our minds is linked to ‘family values’, as Right-wing politicians used to say before an imminent sex scandal, but from the beginning it was almost anti-family, and Jesus told his disciples to leave theirs. Whereas Judaism had been heavily kinship-based, Christ voiced the view that the noblest thing was to lay down one’s life for a friend – a gigantic moral leap. This universal ideal was spread by St Paul who famously stated that there would be neither Jew nor Greek, ‘for ye are all one in Christ Jesus’.

“Although both large Abrahamic faiths are universalist, western Christianity was far more jealous of rival loyalties, such as could be found in the clan, and wanted to weaken them. St Augustine of Hippo and St Thomas Aquinas both encouraged marrying out as a way of widening social ties, and in Summa Theologica Aquinas objected to cousin marriages on the grounds that they ‘prevent people widening their circle of friends’. He wrote: ‘When a man takes a wife from another family he is joined in special friendship with her relations; they are to him as his own.’

“The influence of the Church caused Europeans to be less clannish and therefore made it easier for large territorial magnates to forge nation-states.

“Another consequence was the nuclear family, which developed in the North Sea region around the turn of the millennium. It was influenced by the western European manor system of agriculture, under which peasants managed their own farms let out to them by the lord of the manor, owing him obligations of work. This encouraged adult children to move out of the family home, whereas in most cultures three generations lived together under a paterfamilias.

“With the nuclear family came a move away from group identity and towards the western concept of individual rights and liberalism. It was a revolutionary idea and in parts of the world where the clan still rules it is still an alien one.”

(^_^) read the whole thing on west’s blog!

previously: whatever happened to european tribes? and st. augustine and st. thomas aquinas and big summary post on the hajnal line

(note: comments do not require an email. manorialism.)

human biodiversity (hbd) is very simply the diversity found among and between human populations that has a biological basis.*

each of us is biologically unique. our genomes, our phenomes, our patterns of gene expression, our epigenomes, our microbiomes — none of these are ever exactly the same in any two individuals, even identical twins. yes, you are a special snowflake! you’re not even the same person today biologically that you were when you were six — or sixteen (unless you’re still sixteen, of course). for one thing, your patterns of gene expression as an adult are quite different from what you experienced as a toddler. each individual human is biologically diverse when compared to all other humans and even across his or her own lifetime. (got that last idea from steve sailer, btw.) and while we’re at it, you’re biologically diverse within yourself, too — cell by cell.

additionally, groups of genetically related individuals can exhibit average differences in various biological aspects (see more on this here). for example, immediate family members are more similar to each other genetically — and, usually, phenotypically — than they are to strangers. moving outwards from that circle, extended family members are also more similar to each other genetically than they are to strangers, although less so than are immediate family members. and the circle can be extended even further to: clan and tribe members, traditional villages and regions, ethnic groups, and races, until we reach the human race where we start comparing our collective biological traits to those of other species: primates, mammals, vertebrates, life on earth…. biodiversity in humans also exists between the sexes. remember that the biodiversity found in all these populations — which don’t necessarily have well-defined boundaries — includes features like epigenomes and microbiomes in addition to genomes.

hbd research is conducted in numerous academic disciplines and their subfields such as biology, genetics, medicine, neurology, psychology, and anthropology. hbd research also draws on social, historic, and prehistoric data related to human populations. (there is no separate academic discipline known as “human biodiversity.”)

*i’ve stolen that very elegant definition from claire lehmann.
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this is the first in 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 — you can read them in any order you choose! like to keep things interactive here on the hbd chick blog. (~_^) :

what human biodiversity (hbd) is not
examples of human biodiversity (hbd)
why human biodiversity (hbd) is true
hbd and racism
hbd and politics

(note: comments do not require an email. human biodiversity!)

all i remember from the seventh grade — apart from the time some of the boys rolled the science teacher’s giant globe down the stairs (heh) — was endlessly taking reading comprehension tests. that must’ve been in vogue in education circles back then — check for reading comprehension! sheesh. seemed like every other day we took a comp test.

what i could never figure out at the time was how anyone could get any of the questions wrong on the tests! the tests typically consisted of three or four paragraphs that covered really dull and boring topics and which were followed by five or six multiple choice questions. but we still had the text in front of us when filling in the little ovals, so if you weren’t sure of an answer — was it bob that drove the car to the store or was it dan who took the bus to the movies? — you could just refer back to the text! what could possibly be simpler?! i know now, of course, that people have different abilities and that in any group half will be below average — and i went to a very average school — but at the time i was mystified. (yeah, prolly some of my fellow classmates just screwed around, too, and didn’t even try to answer the questions correctly.)

i have to admit, though, that that old bewildered feeling comes back to me again whenever someone misunderstands what hbd is.

human biodiversity.

it’s just TWO words, for chrissake!! two pretty straightforward words at that! how can anyone possibly misunderstand the phrase?!

ok. deep breath. let’s break it down. there’s “human” and there’s “biodiversity.” biodiversity is, i guess, one of those whatchamacallits — portmanteau words. it’s a combination of biological + diversity. i hope i don’t have to define either of them. and human? well, h. sapiens, i suppose, but if you want to throw in neanderthals or denisovans, that’d be okay.

so, what’ve we got? human biodiversity = the biological diversity of humans (see here). period. full stop.

here is where i’d like to note that human biodiversity is, thus, a set of natural phenomena — like chemical bonds or electromagnetic radiation. hbd is not a group of people — it’s the total variation of biological characteristics that all humans exhibit.

to be more specific: hbd is not an ideology. it is not a political platform. it is not even a set of beliefs. hbd is not a movement. of any sort.

hbd is not conservative or progressive. it’s not republican or democratic or independent or connected in any way to the mickey mouse party. it’s not libertarian, nor does it back a monarchy. hbd isn’t neo-fascist or neo-communist. or neo-confucian, neoconservative, neo-colonial, and/or neo-freudian.

hbd does not have feelings. or ideas. or even principles. it cannot advocate or suggest or imply or argue for or against or promote or claim anything. hbd does not have agency. saying that hbd “supports” anything is as ridiculous as saying that gravity “prefers” fluffy little bunny rabbits or that the second law of thermodynamics “was never really a big fan of” guy lombardo.

human biodiversity is just something we find in nature. that’s all.

there are obviously people who think hbd is particularly interesting — myself, for example. i guess we could be called “hbders” (hbd-ers?) — and here online there is something of an hbd-o-sphere — but that’s about it, really. to refer to the broad range of individuals who are interested in human biodiversity as “hbd” is simply misunderstanding the acronym.
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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!:

what is human biodiversity (hbd)?
examples of human biodiversity (hbd)
why human biodiversity (hbd) is true
hbd and racism
hbd and politics

(note: comments do not require an email. not hbd.)

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.”

• microbiomes. our microbiomes appear to vary between ethnic groups/races.

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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!:

what is human biodiversity (hbd)?
what human biodiversity (hbd) is not
why human biodiversity (hbd) is true
hbd and racism
hbd and politics

(note: comments do not require an email. great moments in evolution.)

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