Live Science and other sources have reported, “New, big-headed archaic humans discovered.” That is Homo juluensis, about which a reader asks a good question. The story “claims to have identified a new human species, similar to but not exactly like the Denisovans. The issue I’m having is with the claim that we share only 6 percent of our DNA with this Homo juluensis. Yet we are told repeatedly that we share 98+ percent of our DNA with chimps.” This claim is an overstatement, but how can this be?

First, let’s define some terms. The idea is that Homo juluensis is a new species, and that the range of species includes a “group” called the “Denisovans.” The “Denisovans” are a mysterious if not hypothetical subgroup of humans from which we only have a few fragmented bone specimens. But because we’ve gotten DNA from a finger bone of a Denisovan juvenile, and a couple of other specimens, we think we know a lot about them. Now the claim that’s being made is that the Denisovans were really part of this distinct new species being called “Homo juluensis.”

A Long-Standing Debate

This raises a long-standing debate among paleoanthropologists about how to classify species. It’s a highly subjective and speculative endeavor. There are two camps. The “lumpers” tend to group individuals together under broad groups, while “splitters” imagine that new species are constantly being discovered. These recent claims that Denisovans belong to an entirely new species definitely come out of the “splitter” camp. However, even Wikipedia admits that “Denisovans apparently interbred with modern humans.” 

That’s a really important statement. It means that according to the standard definition of a species as an interbreedin population, we’re all part of the same species — we are them and they are us. They should not be considered a different species, and this whole “Homo juluensis” claim is just a fiction being invented by splitters who are evolutionists that want to find human-like creatures that aren’t us.

Indeed, all we have of Homo juluensis is a few cranial and dental remains — “Assorted cranial and dentognathic remains,” — as admitted in the technical paper. So how can they justify claims of a new species based upon such limited remains? 

Meet the Denisovans

The Denisovans were a group of humans that lived from 25,000 to 285,000 years ago. As far as we know, they were virtually indistinguishable from modern humans. I predict that the same goes for H. juluensis — although there’s so little data to go on that it’s hard to refute or confirm the claim.

In that regard, any claim that we are only 6 percent genetically similar to Denisovans or H. juluensis is totally false. A report also quoted by the reader — “Denisovans have long intrigued scientists. Despite some modern humans sharing as much as 6 percent of their DNA, limited remains have been found to date” — is simply confused.

I think what they meant to say is that we can confirm that 4-6 percent of DNA in certain modern human populations has markers that are found in Denisovan DNA, and thus we can confirm that the Denisovans were directly ancestral to those modern humans and 4-6 percent of that modern human DNA came from that Denisovan-like ancestor. The Smithsonian Institution puts it accurately on their website:

Comparison of the Denisovan genome to various modern human populations shows up to 4-6% contribution from Denisovans in non-African modern human population.

Similarly, Medlineplus.gov explains:

The percentage of Denisovan DNA is highest in the Melanesian population (4 to 6 percent), lower in other Southeast Asian and Pacific Islander populations, and very low or undetectable elsewhere in the world. … The precise way that modern humans, Neanderthals, and Denisovans are related is still under study. However, research has shown that modern humans overlapped with Neanderthal and Denisovan populations for a period, and that they had children together (interbred). As a result, many people living today have a small amount of genetic material from these distant ancestors.

The key word there is “ancestors” — all they’re saying is that 4-6 percent of DNA among living people from Melanesia (certain islands in the southwestern Pacific Ocean) seems to contain markers known from Denisovan DNA. It doesn’t mean our DNA is only 4-6 percent similar to Denisovan DNA. It just means that we can confirm that 4-6 percent of that DNA came from a Denisovan-like ancestor. And for all we know that ancestor was as human as you and me. 

A Hypothetical Situation

But human ancestry is complicated and we share tons of recent common ancestors with each other and with Denisovans. So we have a lot of other similar DNA in common with Denisovans — this is just saying that we have very particular DNA from Denisovans in common. Think of a hypothetical situation where we compare a 20-amino acid protein found in Denisovans, a Melanesian human, and a Southern African human:

• A Denisovan human protein sequence: LIIDSTIKFDISDWHDAVME
• A Melanesian human protein sequence: LIIDSTIKFDISDWHDAVME
• A Southern African human protein sequence: LIIDSTIKFDISDWHQAVME

Note that 95 percent of the DNA (19/20 amino acids) between the Southern African human and the Denisovan human are identical. But 100 percent of the DNA between Denisovans and Melanesians are similar. That’s because they both share the “D” that is highlighted in bold. So we would say that 1 out of 20 amino acids in this sequence (5 percent) of the Melanesian DNA is “Denisovan DNA.” The rest of the DNA, though similar, comes from some other common ancestor that Denisovans, Melanesians, and Southern Africans all share. 

So the rest of the DNA between living humans and Denisovans is still very similar — I don’t know if anyone has calculated the exact amount but I would be shocked if our similarity was less than 99 percent. We are, after all, the same species! But only 4-6 percent in certain human populations contains markers found specifically in the Denisovans. So we call it “Denisovan DNA.” 

Lumping Back to Reality

At the end of the day, these new “splitter” claims of a newly discovered human-like species should not be taken too seriously. We don’t know that the individuals belonging to “Homo juluensis” weren’t human, and we certainly don’t know that the Denisovans weren’t human. What we do know is that there is an evolutionary motivation to claim that things that looked human weren’t really part of our species. But if humans interbred with these “species,” that claim falls apart.