I thought this was most suited to GQ, even though some answers may be more opinion than factual – mods can feel free to move it if more suited for GD or IMHO.
What are the biggest questions remaining about humanity’s recent evolution and interaction with other homo genus species? A few years ago, I think some of the biggest questions were answered – in particular, whether or not we interbred with Neanderthals (the ancestors of most non-Africans, it turns out, did, along with some other interbreeding with lesser known homo species like Denisovans and perhaps others).
Some possibilities for the “big questions”:
What were the interactions, if any, between homo sapiens and relict erectus populations in Asia and islands?
Why did the Neanderthals go extinct?
When and how did language develop?
Who were the Denisovans and Red Deer Cave people, and what other homo species have yet to be discovered?
When did the first humans arrive in the Americas? IIUC, we have some tentative answers on this, but there is conflicting data.
I’m sure there are lots of others. I find this to be one of the most fascinating subjects in modern science.
Did humans evolve or were they created? … here I’m defining “biggest” as the most number of people discussing it … these questions you’re asking is going to take a college degree in biology to answer, half the world’s population is of below average intelligence and many believe man was created or just simply exists …
Setting that aside, then I’ll take “Need More Fossils” for $1000 … most other sciences have an abundance of data, I pity the human evolutionary biologist where a single tooth is all we have for an entire species …
Since this is in GQ, I presume the OP is referring to scientific questions. There really is no point in bringing up this tangent in GQ, so let’s drop it.
One of the big ongoing major issues is whether modern humans evolved in one place and migrated out (replacing existing archaic humans) or did the existing archaic humans all simultaneously evolve towards modern humans with gene flow smoothing things out or some other variation.
The single African origin is most popular, but there are some uncertainties. In particular, there were several flows of humans out of Africa over the millennium so there could be a mixed picture.
Basically, the more gene testing we do, the more complex things seem.
Look at the Denisovan thing. A single finger bone is all we have. But from that we can ID Denisovan genes and which modern humans have more Denisovan genes than others. We also know that the Denisovans mixed with Neanderthals and possibly another archaic group we know eve less about. How many of these “others” are there going to be???
That debate has been resolved for some time. Modern humans unequivocally evolved in Africa and spread out from there. Exactly where and when they evolved in Africa, the complexities of their migrations into Europe and Asia, and the extent to which they interbred and picked up genes from archaic species is still an active area of investigation.
The broad outlines of modern human diversity and dispersal are known with some level of comfort, but lots more room to keep refining their first entry in any given region, and how subsequent population interaction went.
More interesting and challenging are the interactions with non-moderns who may have been living there [Neanderthals and Denisovans already mentioned and lots of others, given how commonly they are found when they we look]. How those unfolded both biologically [via genes] and culturally [via archaeology] is likely to be different each time, but we seem to have finally gone from the 19th century self-justificatory model of total replacement of the less evolved by the better / fitter / more deserving, to the evidence from DNA which can be read as at least more nuanced and complex.
While we recognise culture via tool use where it involves rocks and bones, which survive well we have very little insight on the development of abstraction, art and social complexity in early humans. What those looked like in pre-moderns and whether it played a significant role in the successful expansion of modern H.Sap is also a biggie.
I think more formal understanding between cultural / societal ‘evolution’ and genetic evolutionary phenomena seem really interesting. Like what is the genetic difference between us and people from the 17th century? Apparently not much [none at all was knocked around a few years back, with a few prominent biologists discussing the end of human evolution], but the rise of science and our connected societies could legitimately be said to have changed humanity.
Or to put it another way - you put some cows in a field and come back in a 1000 years and what do you get? Genetically there’s not much to report, maybe one cow has a shaggier coat, that one over there has longer hooves. They’re still chewing the cud.
Now put some humans in a field and come back in a millenium. Genetically there’s not a great deal to discuss either, but they just built the starship enterprise. So a greater understanding of the physical basis for these sort of developments seems like it could be profound.
It may not be, though. Science is the art of the soluble, as a wise man once said. There are many ideas in science that sounds awesome to the layman, really deep, big questions; that actually end up being a tedious load of shite when we get into them in the laboratory. Too intractable, lack of methods, too open-ended, chronically irreproducible etc. I don’t know if these sort of questions are serious right now [although surely they would have to be at some point].
A lot of this may be a definition issue – what groups do biologists choose to identify & name as a separate species.
Clearly, Neanderthal, Denisovan, and modern Sapiens could all inter-breed. That would seem to indicate that they are all the same species – at least, that used to be one of the defining characteristics when I learned science as half century ago.
Many good species are interfertile and can even produce fertile hybrids. However, according to current interpretations of the Biological Species Concept, if hybridization is limited in time and space, then the two groups can be considered to be separate species. If sapiens and Neanderthals were actually the same species, we would expect that they would have merged entirely where they co-existed. Instead, they maintained a separate identity where they overlapped in Europe for up to 5,000 years. As far as we can tell, interbreeding was limited to a few localities, probably in the Middle East, and for a limited time when sapiens first left Africa. This is what one would expect if the two types were good species. If we had been the same species, we would expect that we would share a lot more of our genome than the 2% found in non-African sapiens. The same considerations go for Denisovans and other archaic forms.
I don’t think high intelligence is an adaptation for survival against environmental conditions, since all other species have survived for hundreds of millions of years without ever evolving it. Instead, it is an adaptation to compete with other human groups. Humans are highly social, and high intelligence provided an edge to compete with other members in the same group as well as with other groups. We keep track of the social interactions that we have had will all other members of the group, and with outside groups, over decades and even passed down over generations. This complex accounting led to an “arms race” in which you had to become smarter and smarter to get an edge over other humans.
A few random thoughts:
Following that line of thinking, it seems that social animals would tend to have greater intelligence. Are there any counters to that?
It also seems like non-social animals have some intelligence, so maybe there is a base amount that allows for effectively finding food and avoiding predators, but advanced levels don’t help?
The fossils dating from around 18,500 BP found in southern Chile certainly raise questions about who first settled the Americas and how they arrived here:
This can only be an opinion, but I feel the most interesting question about human evolution is the how and when of language. Since all human species have it and to the same degree (at least as far as is known) it has to have been pretty much fully evolved before leaving Africa (although, to be sure, there will be a lot of disagreement with that). As far as I am concerned, language is what makes us us. Yes I know about Chimps and Gorillas who have been taught primitive communication systems. Show me a chimp that can use a subordinate clause and I might change my mind.
PLEASE show me a chimp who can use a subordinate clause. I never learned grammar as I should have, too boring, and I would like it explained to me by a fellow primate.
Is this entirely accurate (when you say “our genome”, not “your genome”)? From what I understand, the amount of Neanderthal content shared is a lot more than 2%, it’s just that any one person might have only 2~% of that overlap. I’ve heard around 20% as a figure for the total amount of Neanderthal in our genome.
And Neanderthal genes have been found even in Khoisan people, there’s no need for the non-African qualification anymore IMO.
Monte Verde is old news at this point. The early date has been widely accepted for almost 20 years now. The “Clovis first” hypothesis and the Ice-free Corridor as the first migration route have been dead as a doornail for many years.
So my point stands about mating between Neanderthals and sapiens being rare, and the two lineages being different species. The article also mentions that certain areas of the genome connected to sex are devoid of Neanderthal DNA, perhaps because it reduced fertility.
Where different lineages of sapiens have come together after separation, the result is usually a complete blending of the two populations in the area of contact, unless prevented by cultural factors. This indicates all modern populations of sapiens belong to the same species, according to the modern interpretation of the Biological Species Concept.