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How do we know we are all Homo Sapiens?

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1370780.  Wed Jan 06, 2021 5:19 am Reply with quote

RLDavies wrote:
It seems that at least some South Asian groups are especially prone to diabetes.

There's been a lot of talk about this lately what with diabetes being an indicator for who will be hit hardest by Covid-19. However, I've not seen any evidence yet to show whether this is as a result of genetics or diet.

As my statistician wife repeatedly says, correlation does not prove causation.

1370799.  Wed Jan 06, 2021 7:31 am Reply with quote

RLDavies wrote:
Blacks tend to have more muscle mass than whites of the same height and weight, to such a degree that kidney function test results need to be interpreted differently between the races.

Something within my experience bears on this. One of the main meds I take to prevent rejection of my transplanted kidney is called Tacrolimus. When I first started taking it, and the doctors were trying to establish a suitable dosage for me, it was noted that what turned out to be the correct dosage was very high for a white person, but fairly normal for a black person. This may have been due to my (sadly rather more than of late) muscular build.

1370819.  Wed Jan 06, 2021 8:51 am Reply with quote

dr.bob wrote:
RLDavies wrote:
It seems that at least some South Asian groups are especially prone to diabetes.

There's been a lot of talk about this lately what with diabetes being an indicator for who will be hit hardest by Covid-19. However, I've not seen any evidence yet to show whether this is as a result of genetics or diet.

As my statistician wife repeatedly says, correlation does not prove causation.

That's why I said "it seems". Whether they're genetically prone to diabetes, or prone to excessive obesity which then leads to diabetes, or whether it's purely cultural, is a hard knot to untangle.

1371038.  Fri Jan 08, 2021 8:32 am Reply with quote

I get more stick than Jesus, on here.

Glad the thread evolved beyond my ignorance! :-)

1371068.  Fri Jan 08, 2021 11:10 am Reply with quote

You think so pstotto?

1371106.  Fri Jan 08, 2021 4:08 pm Reply with quote

I was thinking back to the discussion on what constitutes species and subspecies, because there are always anomalies to most definitions, so it's a strange subject. But what level do you consider accepting a population as a species?

One of the most common definitions would be that they will naturally mate in the wild and produce healthy offspring.

That definition is strained by the fact that we humans have moved quite a few species to different environments that has allowed interspecies interbreeding (like lions and tigers).

So I would suggest using another level of definition that then means all humans are a single species, and that's the "ring species" test.

Ring species is a phenomenon in biology where you have subspecies living next to each other which can interbreed with their immediate neighbours, but it's a bit like Chinese Whispers in that as you go from one subspecies to another, there is a point where two subspecies are at such opposite ends that they cannot breed successfully. This creates a strange case of two animals that are classed as the same species, but could technically be argued as being separate species.

A famous example would be the Ensatina salamanders along the western coast of North America. There are several subspecies along the coast. Going from the southern end of the coast in Mexico, all the way up to Canada, and then back down around the eastern side of the Californian Central Valley, each subspecies is able to breed easily with their neighbouring subspecies. However, when you reach Ensatina klauberi on the eastern end of the Californian Central Valley, which creates a sort of horse shoe effect, they are now neighbours of Ensatina eschscholtzii, which populates the coast, but they are so different that they cannot breed, and can technically be considered separate species.

It's basically that subspecies A can breed with subspecies B, who can also breed with subspecies C, and they in turn can breed with subspecies D, and so on. You then get to a point where subspecies A may meet subspecies P, but at that point they are so different they cannot breed at all.

It makes you wonder about why Homo Sapiens survived while other Hominids died out. Could it be that Sapiens was able to breed with some of the other species and therefore survive in various environments, and that other Hominid species weren't able to breed with other species?

Basically, our forefathers where the species that were willing to shag anything that moved and managed to breed in the process, and the other species were more choosey?

1371155.  Sat Jan 09, 2021 11:10 am Reply with quote

We basically incorporated the Neanderthals didn't we?

1371160.  Sat Jan 09, 2021 11:51 am Reply with quote

Probably - the idea is that H. sapiens were generalists with better cognitive processes who out-evolved H. neanderthalensis despite the latter not only being physically stronger but also having a bigger brain in absolute terms.

The study found that early H. sapiens probably had a larger cerebellum than Neanderthals—a part of the brain that, in modern humans, is important for both motor skills and higher cognition, including language processing, learning and reasoning, and social abilities.

The greater range of niches for humans allowed for greater numbers even within the same geographical area and in some way the Neanderthals were subsumed within the human population. You'd have to call the Neanderthals a minor subsidiary at this point however as in Eurasian DNA they contribute only 1.6% to 2.1% of the make-up of modern humans. Assuming evolution 'knows what it's doing', and with human self-determination as a factor that is open to question, the Neanderthals carried roughly that proportion of genes that were of more use than their human counterparts.

1371172.  Sat Jan 09, 2021 2:44 pm Reply with quote

I know that 23andMe tells you how much Neanderthal DNA you have. Woodsman has more than me, as a glance at him might tell you...

1371219.  Sun Jan 10, 2021 9:44 am Reply with quote

The Natural History Museum's Prof Christopher Brian Stringer FRS wrote:
When I drew up a family tree covering the last one million years of human evolution in 2003, it contained only four species: Homo sapiens (us, modern humans), H. neanderthalensis (the Neanderthals), H. heidelbergensis (a supposedly ancestral species), and H. erectus (an even more ancient and primitive species). I have just published a new diagram covering the same period of time and it shows more than double the number of species, including at least four that were around in the last 100,000 years.


In my view, if Neanderthals and Homo sapiens remained separate long enough to evolve such distinctive skull shapes, pelvises, and ear bones, they can be regarded as different species, interbreeding or not.

We're back to the problem of fuzziness; intra species variation and inter species diversity are different extents of the same evolutionary phenomenon which is not well suited to the traditional rigid classification of animals into rigid groups. I think we can say that if animal types are incapable of producing fertile offspring then they are different species but if this is not the case what we have is a snapshot of an ongoing process of uncertain outcome.

The nature of this process with regard to Homo sapiens and H. neanderthalensis changed with the extinction of 'pure breeding' Neanderthals. It has been suggested that their disappearance may have been a consequence of an inability on their part to adapt to climate change rather than a result of any actively aggressive behaviour on the part of humans. Most recently in 2018 new data emerged which might help explain the Neanderthal extinction in terms of humans inhabiting regions vacated by H. neanderthalensis because of their reduced numbers.

Ritter reports that the new palaeoclimate records show that a particularly cold, dry period began about 44,000 years ago and lasted 1,000 years. Another cold dry period began, 40,800 years ago, lasting about 600 years. It was cold enough that average temperatures dropped to below zero, creating year-round permafrost.

Those climate disruptions correspond to the archaeological record, which shows that at the same time Neanderthals began to disappear from the Danube River Valley and in France, the heart of their territory, while early signs of modern humans begin to appear. The paper appears in the journal Proceedings of the National Academy of Science.

While the precise implications of the CI eruption for cultures and livelihoods are best understood in the context of archaeological data sets, our results quantitatively describe the magnitude and distribution of the volcanic cooling and acid deposition that ancient hominin communities experienced coincident with the final decline of the Neanderthals.In our climate simulations, the largest temperature decreases after the eruption occur in Eastern Europe and Asia, sidestepping many of the Paleolithic centers in Western Europe. Acid deposition was intense but short lived, fading to <1% of peak levels within several years after the eruption. Based on these results, we suggest that in isolation the CI eruption was likely insufficient to cause extinction of otherwise healthy Neanderthal populations. However, though the cooling in much of Western Europe may have been limited, it was not negligible. Temperatures in Western Europe decreased by 2–4 °C on average during the year following the eruption. These unusual conditions may have directly influenced survival and day-to-day life for Neanderthals and anatomically modern humans alike, and emphasize the resilience of anatomically modern humans in the face of abrupt and adverse changes in the environment.

Campanian Ignimbrite volcanism, climate, and the final decline of the Neanderthals
Black, BA
Neely, RR
Manga, M
Geology, 43(5) 2015-03-19

Last edited by Celebaelin on Sun Jan 10, 2021 12:54 pm; edited 1 time in total

1371229.  Sun Jan 10, 2021 11:48 am Reply with quote

Jenny wrote:
I know that 23andMe tells you how much Neanderthal DNA you have. Woodsman has more than me, as a glance at him might tell you...

I would possibly take such claims with a pinch of salt:

1371260.  Sun Jan 10, 2021 4:34 pm Reply with quote

For instance, black people's blood clots faster and more easily than white people's. This is seen not only in Africans as such, but in mixed-race "black" populations as in Europe and the US.

Bit of a linguistic quibble here. It isn't that "black people's blood clots faster...." - it's that there are certain groups of people who's blood clots faster, and those groups of people also tend to have "black" skin.

But more importantly - this seems to fit neatly in here..........

1371278.  Sun Jan 10, 2021 6:24 pm Reply with quote

Quite right - what sort of idiot would want to give up language and return to facial expressions, mime and crude symbolism as a method of communication.

Last edited by Celebaelin on Sun Jan 10, 2021 6:32 pm; edited 1 time in total

1371279.  Sun Jan 10, 2021 6:31 pm Reply with quote

Ah - no - you've misunderstood me Cel (or at least I hope you have).

Language matters. By using the epithet "Black people's" and then attributing another characteristic you are giving weight to the blackness of people that indicates another (possibly less visible) characteristic.

It would be equally valid surely to say that "Factor X carriers" (where Factor X is the gene that gives rise to a propensity to faster blood clotting) - so "Factor X carriers will also commonly have a darker skin colour".

The sentences

black people's blood clots faster and more easily than white people's.


Factor X carriers will also commonly have a darker skin colour

whilst conveying the same information, propound entirely different world views.

i do love the flashy graphics btw

1371289.  Sun Jan 10, 2021 8:16 pm Reply with quote

The emphasis on the importance of language was made in the YouTube link you posted bob - it ascribes the success of H. Sapiens to the development of complex thought which language allows.

What I intended to convey was that I think emojis can contribute to understanding by allowing the addition of a mood to a piece of text but I'm not so keen on their completely replacing text as an everyday means of communication.

For my taste that gif cycles too quickly btw but that isn't the point - what I'm saying is that 8 pages of emojis with about 650 images per page isn't a huge capacity for expression compared with the almost limitless permutation and nuance of the written or spoken word but their use may add a dimension to understanding on the part of the reader which a lucid but less emotionally connected section of prose would not impart.

When I see the written word entirely substituted for by a string of emojis it makes me sad because I see it as a lost opportunity for expression and exploration of the elegance, precision and sheer fun of stringing words together.

Truthfully it wasn't my intention to comment about the genetics stuff but since I'm here anyway...

A geneticist would tend to say something like this:

The preponderance of the dominant allele(s) R (,G and D) within such and such a population leads to an average [example physiological response] time of t seconds. The higher incidence of the r (,g and d) allele(s) found in A. N. Other group leads to the slower average [example physiological response] time of t+n seconds. Phylogenetic analysis suggests that the ancestral genotype was ? (, ?, ?). The emergence of the ¿ mutant allele resulted from the selective advantage it conveys in an environment of [given niche element] against which the ? form defines merely baseline protection. (The ? locus is within the Makesomethingup linkage group and the disadvantage the ancestral allele carries relative to the newly emergent ¿ form is outweighed by the selective advantage imparted by the arisal in the parent population of the § variant of the Promakesomethingup Oxidase gene with which it is predominantly co-inherited. The evidence suggests that the ¿ allele increased in incidence relative to ? after post ice age climate change related food species extinctions meant that the members of the group no longer routinely needed their livers to de-toxify [former food component] metabolites and the new form of the gene, while less effective for its now obsolete original function, does impart a benefit in [example physiological response] time.)

Population geneticists don't talk about individuals; at any rate no circumstance springs readily to mind where they would do so - that's exclusively a matter for medical and veterinary geneticists I think.

I'm sorry if that geneticsy bit isn't as clear or as light-hearted as I intended it to be but I enjoyed writing it despite how hard it's been to get the logic of the fictitious circumstance right.



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