Monday, March 13, 2006

Old Age and Human Evolution

by Edward Hugh

Possibly it isn't especially noticeable, but this weekend I've been working on the sidebar. In particular I've added a new category of 'scientific blogs' whole interests one way or another touch on those we have here. Among these John Hawks Anthropology Weblog. This morning I notice that John's most recent post is indeed of interest to us:

".....mortality rates are malleable. They are changed not only by improvements in health, nutrition, and environment across the lifespan; they are also improved by short-term changes in older adults."

John is, as you might imagine from the title of his blog, probably more interested in the Upper Paleolithic than he is in our contemporary issues, but the two epochs are not entirely unconnected in what we can learn from them about the evolution of our lifespan. John's post is also useful since it serves as an introduction to the work of James Vaupel and raises importanbt issues about the relations between genetics and culture in understanding our lifespan.

In so doing he directs us to two other researchers - Sang-Hee Lee and Rachel Caspari
- whose work centres on this topic. In a recent paper Caspari and Lee conclude that:

"the increase in adult survivorship associated with the Upper Paleolithic is not a biological attribute of modern humans, but reflects important cultural adaptations promoting the demographic and material representations of modernity".

Unfortunately this paper is not freely available online, but an earlier paper - Older age becomes common late in human evolution - (published by the US National Academy of Sciences) is:

"Increased longevity, expressed as number of individuals surviving to older adulthood, represents one of the ways the human life history pattern differs from other primates. We believe it is a critical demographic factor in the development of human culture. Here, we examine when changes in longevity occurred by assessing the ratio of older to younger adults in four hominid dental samples from successive time periods, and by determining the significance of differences in these ratios. Younger and older adult status is assessed by wear seriation of each sample. Whereas there is significant increased longevity between all groups, indicating a trend of increased adult survivorship over the course of human evolution, there is a dramatic increase in longevity in the modern humans of the Early Upper Paleolithic. We believe that this great increase contributed to population expansions and cultural innovations associated with modernity."

Incidentally you can find a good selection of Sang-Hee Lee's work here.


Anonymous said...

Older humans are living libraries.

Guy said...

"Older humans are living libraries."

In theory, yes. Much depends on the older humans' willingness and ability to store and process information.

Information acquired, say, thirty years ago may no longer be completely valid today.

I believe that, as we seem to be getting older and older, we need a different way of dealing with information. It does no longer suffice to learn enough to be able to work for the rest of your life and leave it at that. We need to incorporate the idea of change and constant development in our thinking. And we need to learn to make ourselves comfortable with fluidity.

Also, the flow of information is ever-increasing and people may be peaking intelectually at a later age than before. More information = more processing time needed.

If I remember correctly people mature at a later age in affluent societies because of a number of reasons. I still need to look further into this, though. It is quite possible that knowledge maturity sets in later in life as well.

So, maybe we'll get to see 'older human libraries' who are indeed physically older but intelectually younger...

These are just some ideas from a neophyte and I definitely need more time to delve into this.

Guy said...

intelectually = intellectually, of course. Sorry about that, I always forget about form when I am thinking about content and vice versa.

Edward said...

Very interesting. I'm still listening to the podcast I mention in the next post. One of the topics they discuss is 'change is the rule'.

As they agree, of course change is the rule, but it is the pace of change that matters, and the rate at which we are able of adapting to change. If these two are too much out of sync problems may happen, and they may be important ones.

I am constantly impressed by the similarities and analogies between climatic and demographic change.