I have not heard before that Neanderthals were slow breeders. What evidence is this based on? Also, you cannot deny that Neanderthals and modern humans were in direct competition for the limited resources available in Eurasia at the time. That may not be the entire answer to their extinction, but it surely must be part of it.
Sorry, when I said 'competition', I was thinking of the direct 'we killed them off' meme that has been a feature of previous extinction argument, when there is no evidence early humans and Neanderthals killing each other - certainly it could have happened occasionally.
Yes, you are right that they were in direct competition for limited resources which also could have contributed to Neanderthal extinction, given they didn't turn to hunting small game and fish, as far as we know. However, we now know they killed seals, and ate some shellfish. It's hard to imagine coastal people being unable to find
any food at any point in recent pre-history. And yes, there are indications in Neanderthal teeth (and likely contemporary Hs, if they were examined) of starvation intervals, which I would guess might be seasonal - winters may have been very hungry times. And Neanderthals don't seem to have consumed much plant food, which is certainly a disadvantage, but not attributable to direct competition. No humans of the period are known to have stored food, although given how little we really know, they may have.
So we have two populations, both faced with severe conditions, and neither is technologically very advanced over the other, with the major exception of what the women did. There is general understanding that the H.sap. women of the period did gather plant food and likely hunted small game. There is evidence Neanderthal women participated in hunting large mammals along with the men, which makes sense if they weren't eating plant material or small game or fish very often. That is a high risk occupation that coupled with the normal risks of childbearing may have meant Neanderthal women were in even shorter supply than their counterparts.
Add to that a poorer diet, and the possibly higher caloric intake needed for Neanderthal women to successfully bear a child and nurse it, we may be looking at a successful birth rate just a little bit lower than that of our direct ancestors. Given that both populations were stressed at the time, that slightly lower successful birth rate may have been enough to cause extinction.
Caveat: I am not a paleoanthropologist or anything like it; I just find this subject interesting and have done a lot of reading over the years.
Here's where I toss in my entirely personal thoughts, not backed by citation. I see where researchers are coming from with the resource competition theories, but I don't entirely buy it. The human populations were small, and the territory was huge. There was coastal occupation. If game was scarce, it was scarce for everyone, and there is no research evidence I've seen that both populations frequently were anywhere near each other, therefore it doesn't seem likely they were in competition for the same animals.
Then there's coastal territory. Some Neanderthals are now known to have eaten shellfish and sea mammals (seal and dolphin). The seals may have been a seasonal hunt during mating and whelping, when they are easy to catch. Dolphins, I dunno how you'd catch them without at least a raft. Shellfish are available in abundance except when buried under ice.
So I
personally don't think resource competition was a major contributing factor. I think a failure to diversify to small game, fish and plant food was possibly a big contributor, and I think a slightly lower successful birthrate put the nail in the coffin. They simply didn't manage to replace themselves fast enough.
I can't find the original article I read on birth rate, but these articles talk about nutrition and childbearing:
Abstract ( I can't access the paper) re Neanderthals and early humans:
"...Evidence from stable isotopes, faunal remains, and the paleopathology of human skeletons suggest that Neandertals consumed a low diversity diet centered on large and medium-sized terrestrial herbivores. In contrast, populations of early AMHS consumed a slightly more diversified diet. The effect of this dietary shift would have resulted in greater diversity of essential nutrient intake and lower maternal and fetal-to-infant mortality, which in turn would have sparked population increases during the early phases of occupation of the European continent by populations of AMHS. Greater diversity of essential nutrient intake by early populations of AMHS may have been one factor that led to the replacement of Neandertals in Europe during OIS 3."
http://www.sciencedirect.com/scienc...serid=10&md5=e295e183be85da01442cc19fe4aabead
This paper on brain growth:
http://www.pnas.org/content/105/37/13764.full
Sciencedaily article covers similar material:
http://www.sciencedaily.com/releases/2007/02/070218141435.htm
Article in Nat Geo includes some discussion of Neanderthal birth rate:
http://news.nationalgeographic.com/news/2008/09/080908-neanderthal-brain.html?source=rss
