Grandparents a boon to primates and whales

Forums: Science And Math, Science, Whales, Grandparents, Primates
Email this Topic • Print this Page

Grandparents' role in species success.

(From www.abc.net.au science section - thought people might be interested)

Science Home News in Science Features Explore TV & Radio Dr Karl Play

Grandparents a boon to primates and whales
Bob Beale
ABC Science Online
Thursday, 17 July 2003

Helping rear young has made grandparents crucial in some species (U.S. National Park Service)

Humans, whales and dolphins have evolved to live well beyond child-bearing age because this helps raise the survival chances of their descendants, argues a new theory of ageing in social animals.

The classic theory of ageing asserts that fertility is the sole determining factor in lifespan. But in many species, grandparents - and especially grandmothers - can influence natural selection long after their own reproductive years have ended, said Dr Ronald Lee of the University of California at Berkeley, in this week's issue of the journal, Proceedings of the National Academy of Sciences.

"In some species, post-reproductive females make substantial contributions to their descendants, either through direct parental care or through grandparental care," Lee said. "Such contributions continue after birth in all mammals - most notably primates - all birds, many insects, and some fish.

"Post-reproductive bottlenose dolphins and pilot whales babysit, guard, and even breastfeed their grandchildren," he said. Lee's theory may also shed light on why women go through menopause.

He argues that in trying to explain why mortality rises with advancing age, evolutionary theorists have overemphasized the part played by natural selection, which has little or no effect on lifespan once individuals are no longer fertile, because they can no longer pass on their genes.

If a species makes no post-birth investment in raising its offspring, then natural selection for lifespan is indeed likely to depend entirely on fertility, Lee said: butterflies lay many eggs, then die.

But in species where parents have few offspring and invest time, energy and other resources into promoting their children's survival, natural selection should logically favour a longer lifespan, he said. Evidence in favour of that idea can be found in humans, as well as their close relatives among the primates, where the gender that provides most parental care tends to have a longer lifespan.

So, if grandparents promote their children's success as parents in their own right - effectively an economic process involving an inter-generational 'transfer of resources' - even more selective pressure should favour living longer, he argues.

Lifespan depends heavily on the transfer effect, he said, noting that mortality for human hunter-gatherers and other social species where inter-generational transfers occur accords well with his new theory: "The average infant in an Efe huntergatherer group is cared for by 11 people in addition to its parents. Co-operative breeding occurs in some mammals, many insects and 200 species of birds."

In an accompanying commentary, Dr Alan Rogers of the department of anthropology at the University of Utah questioned why evolutionary processes would have promoted early menopause.

"If selection favours production of children, how could it ever favour an early end to fertility? Why do women not continue producing babies into old age? Or to look at the problem from the other direction, how does selection weed out harmful mutations that increase mortality late in life?" he asked.

"The force of selection affecting genes expressed in 50-year-old women should depend on the contribution that such women make to future generations. But if these women have stopped reproducing, this contribution would seem to be nil. Thus, harmful mutations acting late in life should accumulate and death should follow soon after reproduction stops. In most species, this is exactly what does happen. But there are exceptions."

Anthropologists have found clear evidence that older women have a beneficial effect on children and grandchildren in traditional societies, and comparisons with other primates have shown that birth rates are higher in humans than in other apes: "This is all consistent with the 'grandmother hypothesis', which holds that the labour of older women accelerates the rate of childbearing in humans," Rogers added.

He said Lee's complex economic calculations on the transfer of resources between individuals and between generations in a species have reconciled a number of problems in previous attempts to explain early menopause and mortality rates: "This is the most comprehensive evolutionary theory of ageing that we have seen to date," he said.

[email protected]

Topic Stats
Top Replies
Link to this Topic

Type: Discussion • Score: 2 • Views: 3,610 • Replies: 18

No top replies

Hey, Wee Bunny, when you copy and past these things, 'spose you could hit the "Preview" button, then edit out all the crap?

A very interesting article, and one of those which makes me shake my head at research scientists. Like very small children with a new toy, they take their observations as unique, and ignore any evidence already presented (such as by historians, ethnologists, writers of essays, and the like), because, of course, they have discovered yet another "scientific truth." It is heartwarming to think that these boys and girls have discovered the value of community.

0 Replies

Setanta, this is about science, not history. As such, there are proofs required before publication. Not 'observations'.

0 Replies

Dammit - I thought I had edited out the crap!

0 Replies

My point is that there exists a truly hilarious attitude among the devotees of emperical process in a very childish trait of behaving as though they have discovered hitherto unknown principles.

0 Replies

It all does often seem clumsy - research, I mean, in such areas - but every little piece of the empirical puzzle is interesting - and sometimes challenges what we all thought we knew!

0 Replies

I agree wholeheartedly that the process is desireable. There is a charming naivete in evidence among the researchers, in my opinion, however.

0 Replies

Hmm - I confess I only skimmed the article - I found and posted it at work as a conversation starter, looking for work stuff - how so Setanta?

0 Replies

Setanta wants every social scientist to have a grandmother with common sense.

Of course, "common sense" says that mother love protects every child.

0 Replies

if only common sense were real in THAT case!

0 Replies

"Common sense" sometimes leads to a correct answer, sometimes to a bad one. And this actually is a very sensitive topic; prior to the '70s, it was generally taken for granted in the scientific community (and elsewhere, naturally) that the primary function of the mammalian female was to produce and raise children, that she would naturally be 100% devoted to this process, and that, provided other needs were met, she would be able to devote all of her energy to the process. The accepted model has now changed, and it is acknowledged that offspring of social mammals are raised by a network of individuals and not by one mother. The nuclear family is highly unnatural and maybe untenable. (I've a complete lack of eloquence this morning; gotta go get some coffee.)

That said, I've gotta seriously question the posits about the conjecture about the evolution of menopause. Until very recently in our evolutionary history, very few individual females would have survived until menopause. I find it difficult to imagine a mechanism whereby this would be selected for. Perhaps it is a side-effect of some other aging process which does confer an earlier advantage.

(Totally incidentally, studies in numerous insect species have shown that an older female requires more resources to produce fewer and smaller young than younger females, but I'm not sure that has much bearing on this particular topic.)

0 Replies

I found it rather simple minded because it is a given in ethnology that those who survive until their offspring are fertile have always provided child care and education . . . among my ancestors, women of child bearing and rearing age were excused military service (which they would otherwise have been obliged to perform), and were therefore expected to provide weapons training for the young men and women. Cu Chulainn (formerly known as Setanta) was the great mythic hero of the Ulaigh (pronounced "Oo-lee" and meaning the Ulstermen), and he learned his martial skills from two old Scots women.

0 Replies

Replace the phrase "common knowledge" with "hypothesis"
and you are now a scientist pursuing a research grant.

Is it naivete, or a survival mechanism that has evolved within our successive
generations of scientists, conditioning them to "publish or perish"?

Or perhaps some scientists merely like to "do studies", and pick whatever
common sense topic they can easily put together, for instant approval and doctoral status?

I bet we could come up with a study that supports either theory.

0 Replies

Quote:

Or perhaps some scientists merely like to "do studies", and pick whatever
common sense topic they can easily put together, for instant approval and doctoral status?

Actually, there is a lot of truth to this, and it doesn't come from the grad students themselves. Gone are the days when you could stay on for years as a doctoral student. At our institution -- and we're easily in the top third for what we do -- there is a great deal of pressure for our gradual students to at least have a dissertation topic -- and preferably have all research completed -- by their third year.

As to "common knowledge" -- to some people, the superiority of one race over another is "common knowledge." Science and scientists may be excessively narrow and obtusely ignorant of many real-world experiences at times, but at least they adhere to a standard of verifiability.

And as to this particular article -- this was published by ABC. I've a hunch the research conducted was rather more to do with quantifying the effects of present or missing females of advanced age in the social groups looked at, looking at how age is represented in various populations and the subsequent health of that population -- there are all kinds of factors that are actually worthy of study that popular publications aren't going to care about or even look at. What you see here is probably a clumsy review of an abstract of an abstract of a review of a number of publications.

0 Replies

On a side not, but still related, i've known of individuals, going back for more than thirty years, who are expert at grant-proposal writing. They often go fishing, and if they hook a fool at the state or federal level, they'll hire some impoverished grad student to do statistical analysis, and then tart it up as a study for submission. I would say this does not characterize the majority, or even a significant percentage of such grant efforts, but it is definitely a lucrative cottage industry.

0 Replies

Yeah, it's out there. For my part, I work on proposals in a field (biological chem, molecular biol, etc.) where your proposal can't even compete without very substantial and expensive facilities and equipment already in place and the review process is pretty stringent (most of our young investigators' proposals get turned down) -- so I've grown accustomed to federal funding being doled out with considerable caution. This may not be the case in other less competitive and less quantifiable fields.

0 Replies

Yes, research is an interesting area...

In my workplace - child and adolescent mental health - we have endless social work, psychology and psychiatry students forced to do a research based thesis.

Often, what they do is of no benefit to us or our clients (or to them, really) and I once had the bright idea of developing a list of pertinent and fruitful research topics in our area that might guide them.

Of course, the kybosh was put on THAT really fast, because people, of course, feared having areas that they might one day want to research pre-mined.... sigh.

Of course, now that I am supposed to be designing a research project as part of an infant mental health degree, I am looking for a tiny, discrete, simple, not really relevant bit of research to do, myself!

0 Replies

i think if only common sense were real in that case!

0 Replies

It was my understanding that only three species of mammals underwent menopause: pilot whales, killer whales, and humans. They mention bottle-nose dolphins as well.

I thought it was a well-established theory that menopausal grandparents were beneficial to a social species.

Consider a 70 year old woman in a small group, such as a paleolithic band, bearing a child. The chances of her surviving until the child reached maturity would be slight. The burden of raising that child would then fall onto her children. With menopause child-rearing stops, and the grandmother can assist her children with child-rearing.

0 Replies

Grandparents a boon to primates and whales

Related Topics

Quick Links

My Account

able2know