WHAT WE KNOW ABOUT HOMININS

This a time of nearly mind-busting revised scientific understanding of our world, including deep time, alternative histories, “reading” NCI level clues about what’s happening, penetration of outer space, and so on. One of the most disconcerting has been realizing that we didn’t “evolve” from monkeys — nothing so vividly literal — but through mutations of maybe a hundred previous hominins that no longer exist. We discovered these through fossils and through DNA analysis, but also involved is the simultaneously evolving mutations of the land, water, and climate.

None of these changes have ended with us and the world as we know it. If the world changes, we must adapt or die out. But what we do will also change the world, maybe to the point that no more humans are possible. In fact, we are nervously aware that the next hominins may be developing this moment and we don’t even know it. We don’t like “different” people. There is a sci-fi series about children who can fly but are killed by frightened people.

Interest is high about just what ended previous versions of hominins. We’ve known about Neanderthals for quite a while without quite admitting that before they died out, we interbred with them enough to acquire some of their DNA. No one knows why they died out. They lasted a very time, enough to exist through and after five of these planetary climate changes like the one we’re evidently triggering. So now study is underway about the spaces just after kinds of hominins, looking for clues about what ended them.

https://academic.oup.com/mbe/article/17/1/2/975516

One idea is that drastically reducing the size of a hominin population might cause a new improved version of the species to appear. This fascinating article is a little jargonish for some of us, but worth it.

“The demographic effects of such speciations can be expected to have been intense, probably involving significant founder effects due to small population sizes, and they eradicated evidence of earlier speciations, such as the chimpanzee-hominid divergence. In turn, we expect that any genetic evidence of these early hominid speciations would have been covered up by the most recent significant bottleneck. We believe this bottleneck could have been the speciation event at the beginning of the lineage leading to living human populations.

There are two issues to consider here: what is the paleoanthropological evidence of a Late Pliocene hominid speciation, and what is the evidence that this speciation was cladogenic and involved a small population size bottleneck?”

The people who work on this use a phrase: “Earliest Shared Ancestor” or ESA, meaning that mutations become divergent species at some point, like a branching Y, and the ESA is the creature that existed just before the fork, the one shared perhaps by humans and other primates. That is, in science terms, “homo” and “pan.”

“A hominid speciation is documented with paleoanthropological data at about 2 MYA by significant and simultaneous changes in cranial capacity and both cranial and postcranial characters. This marks the earliest known appearance of our direct ancestors. The new species has been called Homo erectus or Homo ergaster by some authors

“. . . in early H. sapiens anatomy, there are four interrelated complexes of changes at the very beginning of H. sapiens (Wolpoff 1999 ):

(1) changing brain size (larger, especially longer vault, with a broad frontal bone and an expanded parietal association area; neural canal expansion);

(2) changing dental function (more anterior tooth use, greater emphasis on grinding and less on crunching) as reflected in broader faces and larger nuchal areas;

(3) development of a cranial buttressing system to strengthen the vault, including vault bone thickening and prominent tori; and

(4) dramatic expansion of body height (estimated average weights double) and numerous changes in proportions). These, and other changes involving the visual and respiratory systems, reflect significant adaptive differences for the new species and give us important insight into the mode of speciation because they seem to happen all together, at the time of its origin.”

“Our interpretation is that the changes are sudden and interrelated and reflect a bottleneck that was created because of the isolation of a small group from a parent australopithecine species. In this small population, a combination of drift and selection resulted in a radical transformation of allele frequencies, fundamentally shifting the adaptive complex (Wright 1942 ); in other words, a genetic revolution (Mayr 1954 ; Templeton 1980).

The significance of this is not just that changes occurred because of a small population that was “inbreeding” which is a concept that has been seen as toxic or even evil since it is prevented by moral limits. We know that groups who do use morality to prevent new genetic input can degenerate into idiots and malformations. This is the opposite of the Nazi notion of “purity”, the idea that there is one version of a species that can be frozen in place. Heredity and conception are processes that must move to persist.

Some Hutterite type groups are locally believed to capture young men, cover them with a sheet that has a strategic hole and bring young women to accept their sperm without either party knowing identities. Heart Butte Blackfeet were once accused of being “inbred” but that comes of not knowing that Canadian Blackfoot members move in and out of the community, bringing new genes. Nevertheless, a lot of kidding goes on about “cousins.” In the pre-contact past, tribes captured women and children to blend into their groups.

At the time the Montana Blackfeet reservation was imposed, Piegans — a sub-group — numbered about 500, half of them children. This meant genetic selection favored those who survived disease, starvation, and trauma. As soon as those burdens were lifted in modern times, the people became big, clever, and tough — restrained only by alcohol and drugs.

Part of the motivation for understanding homo ergster comes from wondering whether the current pandemic will change the nature of our species by removing so many individuals. Whites may be secretly hoping that the extra vulnerability of people of color will mean that a new species will be all white. But their vulnerability is not based on their genetics — rather it is socially imposed.

In fact, knowing the nature of a species has moved from their appearance to their genetic formula. We have been surprised to discover that parrots are descended from hawks and still share much DNA formula. What is important about homo sapiens is not what color they are, but in their genetic interaction with the environment. That level of survival often depends upon cooperation and compassion, not on refusing vaccine and masks. Even so does science of the past guide us forward.