you may have heard that you might have some Neanderthal DNA,
and one of the questions that viewers have asked us is how many chromosomes do Neanderthals have?
well, today, we're going to go over the answer to that question. Howdy,
welcome to Family History Fanatics, where we love helping you climb your family tree and have fun
along the way. Neanderthals were one of the many groups of humans that lived from about
500,000 years ago to around 30,000 years ago. They lived at the same time as some
modern humans in Europe and Asia and actually interbred with modern humans, which is why we
have some Neanderthal DNA. If you have European or Asian ancestry because this interbreeding
only happened in Europe and Asia, what we find is that people with only sub-Saharan African ancestry
don't have any Neanderthal DNA. But the question of how many chromosomes Neanderthals have
is an interesting one because we have to go way back to try to figure out that answer. So
let's start by building a family tree only. Unlike most of our family trees, this one is going to be
way back. And when I say way back, I'm not talking a few generations. I'm talking millions of years.
Now before DNA was sequenced and even discovered, we had been putting together the tree of life
in various ways using different techniques. And interestingly enough, a lot of that tree of life,
once we discovered DNA and actually were able to compare sequences, was really confirmed by the
amount of shared DNA that we have with different animals. So, for instance, humans over here
are closely related to chimpanzees and bonobos. They're our closest living cousins really right
now. Now that doesn't mean that we're really close. We split off from the group that eventually
became chimpanzees and bonobos about seven million years ago. So we're talking thousands
and thousands of generations ago. This was not some recent thing, but that group had split off
from gorillas even longer about 10 million years ago. And orangutans before that and then gibbons,
and finally we get to our monkeys as well. Which was 25 to 50 million years ago. Now when we're
looking at DNA, what we can find is we see that humans have 23 pairs of chromosomes. Bonobos and
chimpanzees both have 24 pairs of chromosomes. Gorillas also have 24 pairs of chromosomes,
as do orangutans. And then we get to gibbons which are much older, and they actually have
a range which the different species of gibbons as far as the number of chromosomes. Just to refresh,
we have, modern humans, 23 chromosomes. Chimpanzees and bonobos have 24. Gorillas
also have 24. Orangutans have 24. And gibbons have between 19 and 26 pairs of chromosomes. Depending
on the species of gibbons. Well, that starts to make our family tree that we've developed
a little bit more interesting. Because we see that hey, if we're looking at this group right here.
They all have 24 pairs, and if we are descended from the same common ancestor that they are,
why don't humans have 24 pairs as well? that's an interesting question, and the reason
is this guy right here. This is chromosome number 2 in humans. The one that you and I have.
Now we knew that there were some anomalies with chromosome number 2 as early as the
early 1990s. There were some parts of it that just didn't line up with what we would expect on
a chromosome. But we didn't know why that was the case? now after we were able to sequence DNA
basically in the human genome project in about 2000, 2001. We're also able to sequence DNA
for many other animals. And one of the things when we looked at our closest genetic cousin,
chimpanzees. We could line up our chromosomes, and we saw that chromosome number 1
lined up with chromosome number 1 on chimpanzees. In other words, we have the same genes on them.
It's approximately the same length. It's a nice match. Chimpanzee did not have a chromosome
number 2 that looked like our chromosome number 2. But their chromosome number 2 looked like our
chromosome number 3. And their 3 looked like our 4 and on down until you got to
chimpanzee chromosome number 12 and 13, which didn't look like any chromosomes that we had.
And their 14 looked like our 13 and on all the way down. This gave scientists pause that hey we have
human chromosome number 2 which we know that there's some anomalies on
that there's no corollary for chimpanzees. And we have chimpanzee chromosomes 12 and 13,
which we don't have a corollary with humans. Is there something between these things? And
some research actually started to figure that out. Now one of the things that can happen
with chromosomes as they divide cells and are passed on is called a chromosome fusion,
an end-n fusion. And that is when two chromosomes basically merge together. Now chromosomes have
these parts called telomeres and centromeres. The telomeres are at the ends. The centromere is
somewhere in the middle. And they have a specific function. So if a chromosome was fused together,
what you would expect to see is not just one centromere but two centromeres. And you'd also
expect to see some telomeres in the middle of the chromosome, not where it's supposed to be.
They started looking at chromosome number 2 and looking at these anomalies in particular. So this
is a representation of chromosome number 2. And on chromosome number 2, we, of course, have telomeres
at the ends. Every chromosome has telomeres at the ends. They're sort of like a protective
cap to keep the chromosome from degrading completely. We have a centromere in the middle,
but one of the anomalies is that there was a section further along that chromosome that
had extremely similar DNA code to what we would expect from a centromere. Now it wasn't a perfect
amount, but it was somewhat similar. Likewise, there was also some DNA code that is pretty much
what a telomere code is in between those two centromeres. And these were the anomalies that
we had known about since the early 1990s. When we took these parts of the chromosome number 2,
and we lined them up with the chimpanzee chromosomes number 12 and number 13.
What we found is that they were extremely alike. In other words, a lot of the genes that we see on
chimp chromosome number 13 are the same genes in the same locations that we see on that upper half
of chromosome number 2 in humans. And likewise for chromosome number 12 in chimpanzees. So what
then was theorized this was in 2005 is that shortly after this split of these family lines,
one that became chimps, one that became modern humans and actually not necessarily shortly but
sometime after that split there was an end-to-end fusion of these two chromosomes. And that's why
our chromosome number 2 is actually the same as chimpanzee chromosome number 12 and 13. Now, this
was a big discovery. So much so that they actually renumbered the chimpanzee chromosomes to now line
up with the human chromosomes again because chimpanzees are our closest genetic relative in
the animal kingdom. So chimpanzees have 24 pairs of chromosomes. They're numbered from 1 to 22,
and then you have your sex chromosomes. And the reason why that doesn't add up to 24 is because
there are two chromosome numbers, twos, 2a and 2b, which align with the human chromosome number
2. Before we continue, if you want to support our work, there's many ways that you can help
in the description below. There are links to our show notes, to free guides, as well as our website
and blog. However, the most important thing you can do is leave a comment and share this video
with your friends. We continue to grow thanks to viewers like you. So let's look at a more recent
family tree of modern humans. I showed you the one that went back 50 million years. Now this one only
goes back about 6 million years. So we are right here, as you can see, and Neanderthals are right
there. They're actually one of our closest genetic relatives in the hominid category. There's still
some debate going around as far as what the actual lineage is. For instance, this over
here is homo heidelbergensis, which some theorize is actually the ancestor of both modern humans
and Neanderthals. Although down below here is homo Erectus which is also another candidate for
homo neanderthalensis and homo heidelbergensis. So we still haven't sorted out exactly how this
family tree fits together yet, but we are really the only surviving hominid of this family tree.
Now, this started about six million years ago, and over time we've had different
branches that have formed new groups, most all of which have become extinct until we get to
our group, the homo group and homo sapiens modern humans. So how do we know how many chromosomes we
have? and that's actually a pretty easy answer. We count them. 1, 2, 3, 4, 5. That's how we know
how many chromosomes. All these animals that we've analyzed have, but there's a caveat there
because normally, our chromosomes are not in a nice countable shapes. They're just one long
string of DNA. And when you think about your cells, you have 23 pairs of these long strings
of DNA. So you have 46 of these pairs of DNA, and they're all jumbled together. They're really tiny
and very difficult to see even under some of our best microscopes. However,
during cell division, during mitosis, and during meiosis, these bits of chromatid clump together
to form the chromosomes. And the chromosomes actually joined together as part of this. And so
you can actually see the pairs of chromosomes, and that's when we count them with during a mitosis or
a meiosis division. That means that these cells have to be alive in order to count them.
Now going back to this tree, we've got a problem here because, as I mentioned, all of these other
hominid species have become extinct. In other words, we have no living cells from any of them,
even our closest ones, the Neanderthals. When it comes down to it, we know that there was
a fusion of these two chromosomes, 12 and 13, from our chimpanzee ancestors, but we don't know
when that happened that. Could it have happened really early on? it might actually be one of
the defining characteristics of the hominid supergroup. However, it might have happened
further on up the tree where we see that some of these groups might have 24 chromosomes, and
really only the homo group has 23. It's also possible that it happened somewhere early on in
the development of the homo group. And so we might see that some of these have 24 and others have
23. So the answer then to this question how many chromosomes do Neanderthals have?
We don't know. We simply don't know. We have some neanderthal DNA that we've been able to extract,
but it is not in a form that we can count the number of chromosomes. We can see where certain
genes match up and line up and how they would fit into the modern human set of 23 chromosomes,
but because of how closely related Neanderthals are to us in the family tree, they probably have
23 pairs of chromosomes. Like I said, though, they might have 24. This fusion might have actually
happened really late in the development of modern humans. Now there's also an outside possibility
that they have something else 22, 25. And that's just because if a fusion happened once, well,
there could have been a fusion or a split or any number of things that happened again during that
line of development for Neanderthals. Now it's highly unlikely to next to impossible that they
have something like 50 pairs of chromosomes, but something around 23 is certainly a possibility.
Maybe not likely, but certainly a possibility. And until we have a living tissue which
I doubt we're ever going to have, you're not going to be able to count
those chromosomes during mitosis or meiosis. So simply put, we don't know. We're probably never
going to know. We're going to assume that they have about 23 pairs, just like modern humans.
But in the end, we don't know. I hope you enjoyed this video. If you'd like to learn
something else about DNA, then why don't you check out this video up here. But if
you want to learn something else about genealogy in general, then check out this video down below.