Tag Archives: Homo neanderthalensis

The Inheritors

40 kya. Neanderthal 1, the first Neanderthal fossil recognized as probably belonging to another species, was discovered in the Neander Thal (=Neander Valley) in 1856. He is close in time to the last Neanderthals: the most recent review of the evidence finds that Neanderthals disappear as a distinct group around 40 thousand years ago. They were almost certainly outcompeted by Homo sapiens who had arrived in Europe earlier. There was probably some kind of coexistence between Neanderthals and H. sapiens over many thousands of years. Regional cultures from this period, like the Châtelperronian, may represent Neanderthals copying the Aurignacian culture of incoming H. sapiens. The final blow may have come between 39 and 38 thousand years ago, when a “Heinrich event” sent cascades of icebergs into the North Atlantic, drastically chilling Europe. Homo sapiens recovered from the cold spell; Neanderthals did not.

Just this year we have learned that one of the earliest modern human fossils from Europe, Oase 1, from Romania (40 kya), has substantially more Neanderthal DNA, 6-9%, than living Europeans. Furthermore, this DNA comes in the form of long stretches of chromosomes, rather than little bits broken up by millennia of recombination, showing that his Neanderthal ancestors go back just a few generations, maybe to some great-great-great-grandparents. We’ve also learned from isotopic evidence that Oase 1 got the proteins in his diet from a broad array of sources, including freshwater fish. Neanderthals, by contrast, look like top predators, gaining nearly all their protein from large herbivores.

And here is some of the art produced by Homo sapiens 40 thousand years ago. lionman The lion man from Hohlenstein-Fels  

And the earliest known cave paintings, from Sulawesi, Indonesia. indonesiancaveart

Talk Like a Neanderthal Day

Like “Talk Like a Pirate Day,” but more scientific!

Human language is probably more than One Weird Trick. It’s multiple weird tricks. We’ve already posted about phonemes, and how they can be strung together to make words. And then words are strung together to make phrases and sentences: but there are a multiple weird tricks here as well. Consider this quotation from some language researchers:

Every human language sentence is composed of two layers of meaning: a lexical structure that contains the lexical meaning, and an expression structure that is composed of function elements that give shape to the expression. In the question, Did John eat pizza?, the lexical layer is composed of the words John, eat, pizza … The sentence also contains did, which has two functions: it marks tense, and by occurring at the head of the sentence, it also signifies a question. (Miyagawa et. al.)

The lexical level of language includes content words: nouns, most verbs, adjectives. The expressive level contains functional words (auxiliary verbs, conjunctions, articles, and so on), as well as tenses and other inflections, and even functional operations like moving around the parts of a phrase. We can think of a sentence like a piece of carpentry, a bookshelf, say. A typical bookshelf will consist of the parts that hold things up (shelves, sides, etc., analogous to lexical structure), and parts that fasten these parts together (dowels, screws, bolts, nuts, nails, glue, etc., analogous to expressive structure).
bookshelf1
But there are other ways to build furniture. For example, here’s a desk with no fasteners. Instead, the load bearing parts have slots and tabs that fit together. This is simpler but less flexible than having boards and fasteners that you can put together however you see fit.
bookshelf2

The analogy with language would be a protolanguage with nothing but content words – nouns, verbs, and adjectives, say – and lexical structure. The analogy works because verbs come with built in slots that nouns can fit into, even without any extra “fasteners” to hold them together. Linguists call this the “argument structure” of a verb. (Think about functions and their arguments if you’re into math or computer science.) For example fear and frighten are both transitive verbs, but they have different argument structures

  • Carg fear thunder.
  • Thunder frighten Carg.

In one case the experiencer goes in the subject slot, and the agent goes in the direct object slot. In the other case it’s the reverse. Some verbs, like burn, have more than one argument structure.

  • Carg burn meat.
  • Meat burn.

English verbs have some tens of different argument structures. (Note that I haven’t put any tense on the verbs. That would be part of expressive structure, which we’re leaving off here.)

So a protolanguage, one step along the way to a full blown language, could consist of a bunch of verbs and their argument structures, with nouns slotted in the appropriate spaces as needed, and adjectives added to convey additional information. Is this what Neanderthal language was like? We don’t know yet, but as we figure out the genetics of language, we’ll find out. For now though, let’s make today – just about the last day on Logarithmic History that Neanderthals are around – “Talk Like a Neanderthal Day.”

Carg publish blogpost now. Next Carg get Oona brunch. Carg and Ooona eat brunch. Goodbye!

Species

We have been treating Neanderthals here as a species, Homo neanderthalensis, distinct from our own species, Homo sapiens. Some researchers elect to call Neanderthals a subspecies, Homo sapiens neanderthalensis, and classify modern humans as another subspecies, Homo sapiens sapiens.

The line between subspecies and species is not clear cut, nor – given the way evolution works – should we expect it to be. Very recent work on ancient DNA recovered from fossils has shown just how complicated the subject is. The spectacular finding of the last few years is that modern humans are hybrids, getting most of their ancestry from a single founding population (we can call them Homo sapiens), but incorporating limited ancestry from close relatives. Thus human beings outside Africa have 1-4% Neanderthal DNA. So it looks as if early in the course of expansion(s) out of Africa, there was a limited amount of interbreeding with Neanderthals.* And not just with Neanderthals. Populations in Melanesia get an additional 4-6% of their DNA from a widespread East/Southeast Asian population known as Denisovans, while some African groups have ancestry from non-sapiens populations in Africa. (The fossil record for Denisovans is a lot sparser than for Neanderthals, and it’s even sparser for African non-sapiens.)

This isn’t reason enough to put Neanderthals and sapiens in a single species: plenty of species occasionally hybridize with related species. And in fact the DNA evidence implies that sapiens and Neanderthals were moving toward being reproductively isolated. Specifically, we find that a lot of Neanderthal genes related to testis development and male fertility are underrepresented (i.e. at a lot less than 1-4% frequency) in modern humans. The likely explanation is that those genes didn’t work well against a H. sapiens genetic background. In other words, if you were mixed sapiens/Neanderthal man, you probably had fertility problems, albeit not to the point of complete sterility.

There is an extensive older literature in physical anthropology on “race crossing.” Researchers were concerned with whether people with mixed racial ancestry might have reduced fitness as a result of combining incompatible genes. This literature is reviewed at book length here. The overwhelming evidence is that “race crossing” has no harmful biological consequences (in contrast to close inbreeding, which is a bad idea). The new data from Neanderthal DNA puts this in perspective. Homo sapiens and Homo neanderthalensis evolved separately for the better part of a million years, and were some way on the path to reproductive isolation. By contrast, different populations (“races”) within Homo sapiens have only been evolving separately for 100 thousand years or less. This has been enough time to evolve major differences in traits like skin color and hair form, but not to create appreciable biological barriers to interbreeding.

And here’s a link covering some recent research suggesting that across a wide range of organisms it takes a surprisingly clock-like average of two million years separation to split one species into two.

* Hence, my Neanderthal name is Carg, and my website is cargshome.

Creb

From 50 thousand years ago, Shanidar 1 is one of the most complete Neanderthal skeletons known, from the famous Shanidar site in Iraqi Kurdistan. He stood about 5’8” tall, on the tall side for a Neanderthal. He died around 40 years old.

The poor guy was also a mess. His right arm had been useless for a while before he died, and he may have been missing his right forearm entirely. His right foot was injured and arthritic, and he must have walked with a limp. He had also suffered a crushing blow to the left side of his head, which healed, but probably left him blind in that eye. And he had a bad scalp wound on his right. Not a pretty picture, but it tells us something interesting about Neanderthal social life: somebody cared enough about this guy to keep him alive, although he was probably too disabled to contribute much as a hunter.

Jean Auel used Shanidar 1 as a model for Creb, a crippled Neanderthal shaman, in her Earth’s Children series (Clan of the Cave Bear, etc.).

Shanidar 3, another skeleton, not quite contemporary with Shanidar 1, tells us about another side of Neanderthal life. He’s got a deep gash in one of his ribs, almost certainly inflicted by a knife or spear point. The wound had begun to heal, so he probably died a few weeks after being injured. An interesting interpretation of this wound comes from Steven Churchill (gated, sorry). In experiments with reconstructed weapons and pig carcasses, he found that the closest approximation to Shanidar 3’s injury came from a spear cast by a spear thrower. Neanderthals are not known to have used spear throwers, so it’s possible that Shanidar 3 fell victim to Homo sapiens moving into the area.

Two roads diverged

50 kya. The broad outlines of the spread of Homo sapiens have been established for several decades now: origins in Africa, expansion out of Africa around 50-45 thousand years ago. But we’re still arguing about the details. For example, based on recent recalibrations of DNA mutation rates, it looks like the African/non-African split might have happened more like 100 thousand years ago than 50 thousand years ago. So the ancestors of non-African (or non-sub-Saharan-African) H. sapiens might have occupied a homeland somewhere north of the Sahara between 100 and 50 thousand years ago, before spreading through Eurasia. North Africa is one possibility. The Near East, maybe the Arabian peninsula, is another possibility. The (or “a”) homeland might be (gated, sorry) underwater, under the Persian Gulf (sea levels were lower then). Both possibilities have some archeological support. There might have been multiple homelands, and multiple expansions – south through Arabia and along the shores of the Indian Ocean, and north through the Levant and into Europe.

A very recent (2015) redating of archeological finds suggests that the Levant-to-Europe corridor was part of the story. A modern stone tool technology, coming from Ksar Akil, just outside Beirut, Lebanon, dates to about 50,000 years ago, a little before much the same technology appears in Europe, in the form of the Upper Paleolithic.

And many other “details” remain to be resolved: What did interbreeding with non-sapiens mean for the evolution of H. sapiens? And just what advantage(s) did H. sapiens have that allowed him (us!) to replace other species? Stay tuned for more on Logarithmic History

African Exodus

Our genus, Homo, left Africa by 1.8 million years ago. But our species, Homo sapiens, left Africa much later, around today’s date, about 120,000 years ago. This skull dates back to then.
skhul5
Skhul 5 was found back in 1935, in Israel, on the slopes of Mount Carmel, buried together with a boar mandible. It looked for a long time like the skull came late in the day, and might represent a transition from Neanderthals to Homo sapiens. But now that date has been moved back, thanks to the development of new dating techniques (thermoluminescence, electron spin resonance) that finally broke the 40,000 year limit for Carbon 14. Skhul 5 now looks like a representative of an early movement of Homo sapiens out of Africa. But the skull also has some Neandethal-like features (check out the “Neanderthal bun” at the back of the skull) and could have hybrid ancestry.

Until recently it looked like this and other very early Homo sapiens outside Africa were a side branch that left no descendants – think Leif Erickson, not Columbus – with the real move coming later. But recently there has been a recalibration of DNA mutation rates that suggests that the split between African and non-African branches of H. sapiens happened closer to 100,000 years ago than 50,000 years ago. And there have been discoveries of stone tools with African affinities in the Arabian Peninsula, in the United Arab Emirates (Jebel Faya, 125 kya) and Oman (106 kya). It may be that when Homo sapiens left Africa 125,000 years ago (perhaps across the Red Sea to Arabia, rather than across the Sinai), they spent a long time isolated in a corner of Southwest Asia before much later expanding more widely.