Denisovan and Neanderthal hybrid

(Jay Johnson) #1

A just-reported analysis of a bone fragment found in a cave in Denisova, Siberia, says it belonged to a woman who was a Neanderthal-Denisovan hybrid.

From the article:

"An analysis of the woman’s genome, reported in this week’s issue of Nature, indicates her mother was Neanderthal and her father was Denisovan, the mysterious group of ancient humans discovered in the same Siberian cave in 2011. It is the most direct evidence yet that various ancient humans mated with each other and had offspring.

“Based on other ancient genomes, researchers already had concluded that Denisovans, Neanderthals, and modern humans interbred in ice age Europe and Asia. The genes of both archaic human species are present in many people today.”

(Laura) #2

Stuff like this is really hard to wrap my head around, since I’ve spent most of my life believing that Neanderthals and their ilk were basically a myth formed by a misinterpretation of a few bone fragments.

Still, this is very interesting. So weird to think about what the world must have been like in those times.

(Phil) #3

Interesting to consider, isn’t it. And whether we consider them as different species, evidently they considered themselves as like kinds.
The paucity of fossils makes me wonder as we tend to put a lot of erroneous information in the gaps.
Along those lines, was looking at reconstructions of modern common animals based on their skeletons similar to way we do dinosaurs. Most were almost unrecognizable without accurate soft tissue structures. Makes you wonder what all we have wrong.

(Laura) #4

True – if our modern divisions of species have a certain arbitrary nature to them, how different were they really, back then? Of course, genome sequencing adds a whole new layer to the available evidence, and I admit my own shortcomings in even scratching the surface of understanding that.

(Jay Johnson) #5

Cold enough to require someone to keep you warm at night, apparently!

It makes me wonder how many other species interbred with closely-related cousins over the course of evolutionary history. We know that Neanderthal and Denisovan contributed adaptive variants in some genes to H. sapiens. How many other hybrids of extinct species with presently living creatures are there? How much did such interspecies breeding affect the genomes of other presently living creatures?

I’m curious whether @glipsnort, @DennisVenema, @sfmatheson, or @T.j_Runyon have an opinion.

(Stephen Matheson) #6

My two cents, unadjusted for currency fluctuation, is that this story is being pitched in the wrong way. By emphasizing that this individual was the offspring of an “interspecies breeding,” we and the news blurb are playing to the part of our brain that thinks there is something important about “species” such that it is big news when two “species” interbreed. Biologically, this is actually pretty silly. Not just because hybridization is common in animals as well as plants. But because the whole conversation is predicated on our sense that these “species” are “distinct” in some really important way.

In this case (ancient humans), in fact, we have long known that they interbred and were therefore not biologically reproductively isolated. The interesting question, then, is the opposite of what the brouhaha would suggest. That question is here, from the end of the Science piece cited in the OP:

That highlights the question, Krause says, of why Denisovans and Neanderthals nevertheless remained genetically distinct groups. “Why don’t they come together as one population if they come together from time to time?” Geographic barriers probably played a role, he says, but researchers need more fossils with ancient DNA, from multiple sites, to understand the true legacy of these prehistoric couplings.

In short, it’s not the mating that’s interesting. (I would add “at all.”) It’s the separation of these populations. Geography? Lifestyle? “Culture”? Now those are interesting questions.

(Dennis Venema) #7

Sex sells, even if it’s in the paleogene, I guess.

There’s also that evidence of introgression into the Denisovan genome (or perhaps long-term population structure). It’s a reasonable hypothesis that Denisovans interbred with H. erectus (or some other hominin we don’t know about). Species only look like isolated groups when we have less evidence, not more - as evolution predicts.

(Jay Johnson) #8

A fascinating perspective. Sounds like we are looking through the microscope when we should be looking through the telescope.

Could you elaborate on this?

(Dennis Venema) #9

Sure. Basically if we had an absolutely complete data set, we’d be hard pressed to draw lines of demarcation anywhere.

With humans, way back in the 1800s, we saw humans as a very biologically distinct group compared to other living apes. Since then we’ve muddied the waters with more data: other extinct hominins, allele flow between then, and so on. The more we know, the harder it becomes to draw species lines.

(RiderOnTheClouds) #10

To speculate, did Neanderthals and Denisovans have a soul? Were they in the Image of God? Were they equal to humans before God?

(Matthew Pevarnik) #11

You may like this review of Christian responses:

My personal take is your question reminds me of the end of John’s Gospel where Peter asks “Lord, what about him?” And Jesus replies (paraphrasing): “What is it to you? You go bear my image."

(Jay Johnson) #12

While the exact location of the line between “human” and “animal” may remain a secret hidden in God, Christians nevertheless will continue to debate whether Neanderthal, Denisovan, H. erectus, all hominins, or only H. sapiens should be thought of as “human.”

Without claiming a definitive answer, I offer my own educated guess. On the analogy of “the man” naming the animals, I suggest the first speakers of words are adam, the first members of the human family. Since the Neanderthal hyoid bone (required for almost all vowel sounds) is nearly identical to our own, we can infer that they also possessed speech, which implicates our most likely common ancestor, H. heidelbergensis, as the first hominin to speak words, probably around 700,000 years ago. Consequently, all of our ancestors from that point could be considered human, although, like children, they were immature and still developing.

Were they in the image of God? I’ll skip this one for now, if you don’t mind. :wink:

Did they have a soul? I’m inclined to Middleton’s view, which @JRM expressed as Humans created mortal, with the possibility of eternal life.

Addendum: Perhaps @Joel_Duff would like to weigh in.

(Laura) #13

This is a tough one, because even among YEC groups, who typically draw a very strong line between “human” and “ape,” they still don’t always agree on which of these groups were actually human and which were not.

(Albert Leo) #14

Yes, Stephen, those are the interesting questions. And modern science concentrates so heavily on genetics and the biosphere, citing reproductive isolation (due to incompatible genes) as the source of speciation. Thus ‘lifestyle’ and ‘culture’ tend to be downplayed . Of course these are part and parcel of what Chardin dubbed the Noosphere, (transmissible ideas), and it is evolution in that sphere that is changing human nature more rapidly than biospherical change.

The meeting between the Neanderthal lass and Denisovan lad, that led to the hybrid that has been featured in recent news, probably was not a common occurrence. It is likely that they did NOT share a common language or a common lifestyle. If the tryst that produced a hybrid child was not merely the result of momentary lust, perhaps they found ways of communicating that would lead to a lifelong attraction. If so, it would be a Noospheric compatibility (lifestyle) that encouraged the cross-breeding, not just compatible alleles. Since the two populations appear to have largely remained separate, such long term relationships must not have been common.

Just some food for thought.
Al Leo

(Phil) #15

It is fun to speculate, though agree that we will not ever really know. I suspect these different hominins freely interbred, but had different geographic and ecological ranges, so meetings were not common. However, they must not have been rare, as it is unlikely we would just happen the find the offspring of such a meeting if it were a one in a million pairing. The offspring must have been well integrated into the social structure and reproduced freely also, as the article stated, as this bone was from a teenager, and most telling is that we now carry those genes in populations around the world.

As to a soul, God only knows. If you propose a unique individual Adam and Eve created at the beginning of agricultural life in a world full of humanity, I think we have discussed the problems that brings in other posts.

(Chris) #16

The simple answer is that they were the same Kind.

Someday we will have to abandon the naive definition of “species” if for no other reason than it has been defined improperly for so long. Perhaps “baramin” will replace it, perhaps some other word.

(Phil) #17

Ha! I used the word as an intentional pun, even though I think that definition is somewhat contrived and not what the biblical text means, but species is an arbitrary delineation of a seamless pocess, so your point is taken as to its fluid and inexact meaning, though I doubt it will be replaced anytime soon.

(Chris) #18

Were they ever two different species? From reading Kathy Reichs novels I gather that different races today can identified by skeletal remains. Palaeontologists finding such remains would probably say they were different species. Similarly based on genetics the African elephants have been split into two species even though there are existing hybrid populations.

“Species” are not very well defined. Paleontologists work from bones, naturalists work with dead specimens, geneticists work with DNA, and ecologists work with living communities. Each group has its own definition, and very often they are in conflict with the others. Sheldon

(Matthew Pevarnik) #19

Morphology is important but genetic analysis can help clear up and refine relationships of ancestry. Here is one such graph:

image Source

(Joel Duff) #20

Just a few words about the recent discovery. First, if further analysis continues to confirm that this is the fist generation hybrid of Denisovan and Neanderthal it will surely go as one of the most fortuitous fossil finds in history. Consider that such hybrids are not likely to be common and the chances of being preserved to the present. Second, amazing at it is I suspect it is just the beginning of many discoveries to come that will continue to shape our understanding of hominid history. We still need more samples of individuals at different time-frames to better understand the genetic diversity present in the population. At present we can’t be sure that we haven’t just sequences a few individuals that only poorly represent the ancestral populations. But what many have missed in this paper is how they came to recover the sample. I believe is was identified as hominid by college amino acid sequence. This is a very new method (<5 years) in the paleontology community. Collagen is well preserved over time and fragments can be sequenced which tell us roughly why type of organisms even a scrap of bone came from. Archaological digs often recover hundreds of thousands of pieces of bone for every single large piece of identifiable bone based on morphology. This new method allows researchers to scan thousands of scraps and identify hominid bones where it was not possible before. Once identified they can try to sequence DNA just like they have in this case. This suggests that there may be hundreds of pieces of bone representing hundreds of individuals already sitting in drawers of labs waiting to be sequenced much less a concentrated effort to find more in the field.
Regarding how Christians will react to his latest find. As cool and stunning as it sounds I doubt it will have a big impact. YEC will claim they already new these were just different races of a single kind and so it is no surprise. It would not be unreasonable to believe that hybridization is possible. The question is whether this was rare (it appears so but we need more data). If it was very rare that would suggest the possibility of significant genetic and cultural divergence between these groups with hybridization under unusual circumstance similar to coyotes and wolves which generally ignore each other and don’t interact and yet have interbred from time to time. Genetically we know that Neanderthal and Denisovans (from the sequences we have) were about twice as different from each other as any two human beings alive today but there are species of other organisms that exhibit similar amounts of variation within the species so genetic data along doesn’t give us a definitive answer about species limits.