Anthropology.net

A new paper in the journal Antiquity interprets the remains of 34 found buried in the village of Talheim, in south-west of Germany as evidence that Neolithic men fought to secure women. The paper is titled, “Isotopic signatures and hereditary traits: snapshot of a Neolithic community in Germany.”

The remains were excavated in the 1980s and dated by carbon-14 to be 7,000 years old. The majority had been killed by a blow to the left side of the head. This suggests most of the victims were bound and executed, probably with a stone axe. The other remains that show signs of arrow-wounds from behind, as if the victims had tried to flee.

Using isotopic analysis, the authors were able to determine the different origins of the people. The three isotopic (strontium, oxygen and carbon) signatures indicated there are distinct groups of people in the burial. The isotope signatures also correlate with the hereditary dental traits of each group.

One group, with isotope signatures derived from upland areas, includes two men, which as I understand it are two of the attackers that died. Another group, the local group, includes many local children among the adult male remains. But there were no adult women, suggesting they had been selectively taken alive at the time of the massacre. The researchers conclude the absence of local females indicates that they were spared execution and captured instead which may have indeed been the primary motivation for the attack.

The basis of this paper supports a common concept in sexual selection, where the limited reproductive capacity of females compared to males drives male–male competition. Males, the less limited sex, compete aggressively among themselves for access to the limiting sex. Lead author, Alex Bentley summarizes,

“Our analysis points to the local women being regarded as somehow special and were therefore kept alive.”

What do you think about the conclusions?

PNAS has just published a back and forth discussion between John Skoyles and Deborah Rogers and Paul Ehrlich. John Skoyles expressed beef with the paper Deborah Rogers and Paul Ehrlich recently put out. The jog your memories, Roger and Ehrlich wrote, “Natural selection and cultural rates of change.” I covered that paper in a February post, raising some questions.

I was not alone in my criticisms, Skoyles also had a set. In his letter, “Natural selection does not explain cultural rates of change,” he wonders two things. First, Skolyes addresses whether or not Rogers and Ehrlich established enough of an argument to inferring that natural selection was at play in how canoes design changed. Secondly, Skoyles takes a shot at how Rogers and Ehrlich use the term cultural evolution. Cultural evolution can be used analogous to cultural change or it can be under the principles of natural selection.

Rogers and Ehrlich defended their work in their response, “Reply to Skoyles: Natural selection does appear to explain some cultural rates of change.” Their response is pretty conservative. They write, “although it does not prove that natural selection was at work, it certainly supports that inference.” I still don’t fully see how differences in the rates of change in frequencies of various cultural traits over time infers natural selection, especially when people are the selectors. It seems like another level of selection is at play.

On that note, the University of British Columbia put out a press release on the work of Liane Gabora, who is making a computer model that will piece together the process by which human culture evolves. She’s made some comments that are directly tangential to the discussion between Skoyles, Rogers, and Ehrlich. She says,

“For one thing, artifacts do not change solely through random, ‘mutation-like’ processes. Humans innovate strategically and intuitively, taking advantage of the ability to group items that go together, like mortar and pestle, or use analogies…

…The underlying mechanisms by which culture evolves are superficially similar yet profoundly different from those through which living things evolve. A symptom of this profound difference is that biological evolution prohibits inheritance of acquired characteristics.”

Skoyles, J.R. (2008). Natural selection does not explain cultural rates of change. Proceedings of the National Academy of Sciences, 105(22), E27-E27. DOI: 10.1073/pnas.0802586105

Rogers, D.S., Ehrlich, P.R. (2008). Reply to Skoyles: Natural selection does appear to explain some cultural rates of change. Proceedings of the National Academy of Sciences, 105(22), E28-E28. DOI: 10.1073/pnas.0803570105

Afarensis has just blogged on this new PNAS paper, “Dating the late prehistoric dispersal of Polynesians to New Zealand using the commensal Pacific rat.” The goal of this paper is to clarify when New Zealand was peopled. There are several hypotheses floating out there, two of which indicate New Zealand was either peopled 1,200 years ago or 800 years ago.

One hypothesis, suggested in this 1996 Nature article, “Arrival of rats in New Zealand,” indicates people arrived with rats roughly 2,800 years ago. This was established using carbon dating of rat bones. Rats, as explained by Afarensis, are often used as a proxy to understand human migratory patterns, because rats and humans have a longstanding commensal relationship. In February, I shared some news on how rats have been used to understand migrations of humans in the Neolithic.

I’m not a rat biologist, and I don’t fully know their ecological independence. Through my personal experiences, I understand rats have been pretty dependent on humans but because these rat bones were dated to be 2,000 years older than the first human remains in New Zealand and were excavated with no supporting ecological or archaeological context, the dates have been hotly contested.

The authors of this new PNAS revisit this study and included carbon dating of rat gnawed seeds from two caves in New Zealand. The authors hope to re-clarify the presence of human occupation of New Zealand because it just doesn’t seem feasible that rats could live for so many thousands of years without humans.

Here’s a summary of the results, from Afarensis’ blog post,

“The research specifically focussed on plant seeds from plants that had been driven to extinction by the Pacific rat (or the rats have been implicated as a possible cause). All the rat bones date to 1280 AD or younger. The un-gnawed seeds are the oldest, whereas, none of the gnawed seeds date to before approximately 700 years BP. This current research dovetails with dates on rat gnawed snails.”

The new dates all confer with the time humans are understood to be present in New Zealand, but one thing that wasn’t discussed in the PNAS paper is other sources of the ratting of New Zealands. Like I said, I’m not well versed in rat ecology. I know they live in close association with humans but that doesn’t mean rats are dependent solely on humans… they just benefit from living next to humans.

See the genus Rattus is thought to have emerged from the Murid family about 3.5 million years ago in Asia. This is well before human ancestors ventured into Asia. They did fine for a couple millions of years there, living in colonies independent from humans. It is possible that rats can live in areas without a human presence.

So if we agree that rats can live by themselves, how did they get to New Zealand? 3,000 years ago, sea levels were about the same level as they are now. Janet Wilmshurst, pictured above, and one of the authors of this paper, told the press that this particular species of rat, the kiore, “cannot swim very far, it can only have arrived in New Zealand with people on board their canoes, either as cargo or stowaway. “

I feel that Wilmshurt is treading on very fine line, speaking with such vindication that these rats had to have come to New Zealand along with humans. Many of the non-marsupial mammals of Australia came by island hopping and rafted from the north, it is possible these rats did the same.

Wilmshurst, J.M., Anderson, A.J., Higham, T.F., Worthy, T.H. (2008). Dating the late prehistoric dispersal of Polynesians to New Zealand using the commensal Pacific rat. Proceedings of the National Academy of Sciences, 105(22), 7676-7680. DOI: 10.1073/pnas.0801507105