Neanderthals nesting in our family tree

Neanderthal skull recreation

Neanderthal skull recreation by the biology department at Wilfrid Laurier University. Photo by Grace Protopapas.

Name calling someone a  ‘real  Neanderthal’  is  not intended as a compliment.  Yet science is telling us we need to understand that Neanderthals co existed with humans and, as it turns out, did more than just co exist. Researchers found most people outside of Africa  are part Neanderthal.

Can you really blame intelligence, or the lack thereof,  on genetics? Probably not. Knowing the intelligence of Neanderthals  from studying Neanderthal DNA is a crap shoot. Fact is, scientists’ knowledge of Neanderthal DNA is patchy at best. However, scientists do know some things for sure.

“We found a genome that is much closer to us than the chimp, so we can use it to study certain pieces of DNA that are unique to human lineage. We can also understand our adaptations to new environments, because it is a question of whether or not Neanderthals helped us adapt,” says Damian Labuda, a genetics researcher and professor at the University of Montreal. He was one of the first to prove Neanderthal DNA was in the human genome.

They also know most Africans have no Neanderthal genes from Neanderthal-human interbreeding. East Asians, Europeans, South-Asians and Native Americans – everyone else – has equal amounts of Neanderthal DNA.

Does your friend have autism? Or a particularly large chest? Red hair? O blood type? Scientists have  speculated these human characteristics are a direct result of Neanderthal interbreeding.

Of course, it’s all speculation. Scientists, like Svante Pääbo, whose team sequenced the whole Neanderthal genome, know certain genes do certain things like make eyes blue or green. However,  they also know up to 97 per cent of our DNA has uses that are unknown. Much of it may be dead weight. So that means of 3 billion DNA base pairs, 291,000,000 may have no function at all.

Pääbo analyzed the Neanderthal genome for similarities to humans and found humans and Neanderthals share 99.7 percent of the same DNA. Most of that is because we share common ancestors. What researchers have found is that part of that – one to four per cent in non-African people – may have come from interbreeding, not from shared ancestors.

Damian Labuda is a professor in pediatric medicine at the University of Montreal and a researcher in the Robert-Cedergren Center in Bioinformatics and Genomics. He led a team studying the human X chromosome. In their work they found unusual DNA, about 100,000 base pairs long. Early on, they flagged the DNA as Neanderthal though it was just a guess at the time. Fast-forward to 2011 when the Neanderthal genome was unveiled: Labuda and his team quickly compared human to Neanderthal DNA, and lo-and-behold the unusual human DNA was indeed Neanderthal.

This discovery gave the world solid proof that humans and Neanderthals had sex.

“First we wanted to know our origins. We wanted to understand our selves, from where we came, and what is the structure of our DNA. This is why we should go to Mars, and why we send telescopes to space: because we want to know where we come from and where we go. This is the most important argument: knowledge,” said Labuda.

Though the fact of its existence is exciting, the chunk of DNA is not, admits Labuda.

“In my opinion, this is totally neutral. You cannot exclude that there are any functional pieces within this, but it doesn’t look like it has any selective advantages. It probably stayed because it was not harmful,” said Labuda.

Basically, this DNA does nothing. Scientists call this  “junk DNA”.

Labuda’s was one of the first confirmed pieces of DNA from Neanderthals, but other researchers have identified similar chunks of DNA.

Neanderthal skull recreation next to human skull

Humans and Neanderthals coexisted for roughly 200,000 years. Photo by Grace Protopapas.

Some speculate that the Neanderthal in many humans may cause autism, immune problems, and blood problems. However, proof of any of this is in short-supply because of our limited understanding of human genetics, let alone Neanderthal genetics.

Neanderthal DNA is so old that making sense of it is hard. Pääbo’s Neanderthal genome comes from 38,000 year old bones. In that time, bacteria, residue and other organic material may have contaminated the pure DNA, said Roger Bull, who works at the Canadian Museum of Nature in the DNA lab.

DNA also degrades over time. DNA is composed of four chemicals, adenine,cytosine, thymine and guanine. Cytocine (usually designated by the letter “C”) turns into a different chemical, uracil, which the DNA reading machines read as thymine (usually designated by the letter “T”. Basically, one quarter of the DNA becomes ambiguous. Anything read as a T could be either a T or a C.

It’s like a Rubik’s cube, only you’re colour-blind to red and orange. How do you know if you got it right?

While Pääbo’s genetic map has been ground-breaking, it certainly isn’t perfect. Many gaps exist. Bacteria is used to reproduce thousands of copies of Neanderthal  DNA, which then gets put into computer programs that try their best to patch up the holes. Nonetheless, about one-third of the DNA is guesswork.

Increasingly, researchers see Neanderthals in a different light. Were they really just less intelligent versions of us? Or were they as smart as modern humans, just less lucky? Either way scientists know that humans and Neanderthals coexisted for roughly 200,000 years. Whether it was their flat heads, bushy fore arms, or protruding brows, homo sapiens found something attractive in Neanderthals because now most of us have a little bit of Neanderthal in us.

Family tree of human evolution. Graphic by Grace Protopapas.

Co-produced by Grace Protopapas.



Tags: , , , , , , ,

Comments are closed.