Where did you read that?
I’m not understanding something here … we’re saying that modern humans “have” Neanderthal genes and let’s assume 2% here … however, from SciAm we see that chimps and modern humans are only genetically 1% different …
So, does that mean we’re more closely related to chimps than Neanderthals? … that makes no sense a’tall …
I just checked my 23 and Me report. They used to give it as a percentage and I think mine used to be 3.6. But they aren’t listing it that way anymore, they just say less than 4%. I’m in the 94th percentile of their database with 316 Neanderthal variants.
They test 1436 markers. I had 2 variants on 30 markers and 1 variant on 256 markers.
From a practical POV, all that they tell me is that I’m unlikely to have a hairy back or to sneeze after eating chocolate. :rolleyes:
Basically, this fits with my discovery via 23 and Me that I’m REALLY white. And Northern European. All rumors of a more exotic ancestry - and there were rumors- were debunked by my 23 and Me testing.
Humans and Neanderthals are just about equally similar to chimps, but each group has a few different differences. Let’s say that a chimp word has the spelling abcdef. But in most populations of modern humans, the word has changed to abcdgh. Except in many Europeans, the spelling has changed to abijef. Then scientist manage to sequence the Neanderthal genome and find that they also spell that word abijef. This fact is strong evidence that Europeans picked up that spelling from Neanderthal ancestors.
Taking another bite of the apple, in both humans and Neanderthals, 99 percent of our genome is spelled the same as in chimps, but in each group, the typos are different. When distinctive typos are found both in Neanderthals and in a subset of humans but not in most other humans, it is an indication those genes likely were inherited from Neanderthal ancestors. But there are other genes that are spelled identically in humans, Neanderthals, and chimps. When the spellings are identical, it is not only impossible to determine if that gene came from a human or a Neanderthal ancestor, but also a question without meaning.
It’s… complicated. Here’s a thread I started many moons ago on that subject.
Thanks … that might be the best information available …
Wiki suggests that this is uncertain:
The statements refer to different things.
One way to measure DNA divergence between species is to align the genomes and look at differences that have arisen through base substitution. This is a kind of mutation where just a single base changes. It is particularly important for phylogenetics, because it tends to occur at a regular rate through evolutionary time, providing a molecular clock that can show which species are more or less closely related. If the clock can be calibrated through other lines of evidence, this measure of divergence allows us to infer speciation times.
(Bear in mind that the base substitution rate does not reflect other kinds of differences. There are also many insertions and deletions, from one base to large segments of DNA; there are duplications of segments of DNA; and in the human lineage the fusion of two entire chromosomes. These differences may obviously be important, but they are more difficult to quantify in a precise way.)
If we look at genome divergence with this base substitution approach, we find that human and chimp DNA sequences have diverged by the oft-quoted figure of about 1%. In other words, since the human-chimp common ancestor around 4MYA, the number of single-base substitution mutations that have accumulated is around 1%.
Using the same method, human and Neanderthal genomes differ by just 0.3% - as you would expect, with a more recent common ancestor.
Now for the claim that around 2% of the human genome comes from Neanderthals. This is talking about something completely different. The speculation is that long after we split into essentially distinct populations, recent interbreeding between humans and Neanderthals occurred, and that the now-extinct Neanderthal population contributed a small amount (perhaps 1%-4%) to the human genome, a process called admixture.
How do researchers claim to know this? The human and Neanderthal populations diverged from a common ancestor into separate populations around half a million years ago, and in that time their genomes diverged by the 0.3% base substitution figure described above. These base substitutions are exactly the same things as the SNP (single nucleotide polymorphisms) markers that are used in DNA tests to identify your genomic ancestry as originating from populations in various parts of the word. In just the same way, a segment of DNA that carries the specific 0.3% of SNP markers that are found in Neanderthals marks the entire segment of DNA as being of Neanderthal origin, even though it is 99.7% identical. So, the evidence for recent admixture of Neanderthal DNA is that 1%-4% of the genome of non-African humans has the characteristic Neanderthal SNPs. But, again - that 1%-4% figure refers to the entire segment length that came from Neanderthals. 99.7% of the sequence in those segments is identical among all humans (African and non-African) and Neanderthals.
It’s exactly the same thing as doing a DNA test and finding out (to your surprise) that 20% of your DNA comes from (say) Asian ancestry. That 20% refers to the total segment lengths that are identified as of Asian origin by the rare SNP differences, and it doesn’t contradict the fact that all humans share >99% sequence identity.
Thanks for that concise explanation. Just a minor correction in that the human/chip split is thought to have happened 5-7M years ago. By the time you get to 4M years ago, our ancestors were already walking upright.
That is not to say that there might have even been some interbreeding between the populations then, but at 4M years ago our ancestors would be noticeably unchimp-like below the neck.
Which is why I said that it was Toba* or not *Toba…
That’s not very convincing. Since the actual cite for the claim is not referenced, I’m going to guess that someone threw out a number that was the minimum there could have been for us to have survived at all, rather than the minimum that the data actually suggests.
The whole idea of a human bottleneck is controversial, and if there was one, the general consensus puts it somewhere between 2,000 and 10,000 individuals. Maybe even more.
Question is then are Homo Sapiens Sapiens, in our modern form actually a hybrid species? Not truly a “pure” Homo Sapiens Sapiens given the influx (albeit thousands of years ago) of Neanderthal and Denovisan DNA?
Like if say the different Human species were separate, distinct branches of an evolutionary tree, did the intermingling of the different species cause the end of the pure Homo Sapiens branch?
I guess it’s very difficult to be that accurate and they’re covering themselves, although it would be interesting to look at the study in question.
I’m not sure anyone can really answer that question.:dubious:
The idea of a “species” is actually a blurry concept. If define different species as two groups that cannot interbreed and produce viable, fertile offspring then Humans, Neanderthals, Denisovians, spit ghosts, etc. obviously aren’t different species. If you define different species as two groups that most of the time don’t interbreed, but on the occasion that they do, sometimes the offspring may be viable and fertile, then Humans, Neanderthals, Denisovians, and spit ghosts were never separate species to begin with. So calling each group different species or calling them different subspecies or races of the same species is a definitional problem.
Isn’t this exciting!? This is us trying to understand of our human ancestry and often what we were certain of last week has been dramatically changed by some new finding yesterday. And discoveries of that magnitude are happening every month or two. It makes it hard to keep up with, but Wow!!!
The discussion on the shared genetic legacy we have with Neanderthals etal reminds to recommend The Inheritors, by William Golding. A fictional account of the way the encounter may have happened. Better than Lord of the Flies - 4 chefs hats at least.
While we were distinct human lineages, in reality our overall appearance and limited array of material culture was probably not very different. Just like crocodiles and alligators, the genetic distance is invisible to the naked eye, while the overall similarities would be all too evident.