The grandmother factor: Why do only humans and whales live long past menopause? | Hacker News Reader

The grandmother factor: Why do only humans and whales live long past menopause?

scientificamerican.com

33 pointsalexandros22 comments

It's an interesting article, but surprisingly light on details, even for Scientific American.

Here's the actual paper: http://rspb.royalsocietypublishing.org/content/early/2010/06...

And here's a delightful book that hits this topic and more: http://www.amazon.com/Mothers-Others-Evolutionary-Origins-Un...

Sarah Hrdy is one of the absolute best popular science writers out there. This and her earlier book "Mother Nature" are two of the best unsung biology books I know of. I've given multiple copies as gifts.

Edit: Having now read more of the referenced paper, my opinion of the Scientific American article drops further. The key detail left out of the SA summary is that the paper describes an interesting mathematical model, rather than yet another 'just so' story. Read the paper, skip the summary.

And now we cicumvent all evolutionary purposes, by moving across the country, and having children in our 30's, making it very hard for the elder generation to become involved with our children's lives.

Of course, the ease of moving across the country has been facilitated by advancements in transportation and communication, and the trend of people having children in their 30s is likely correlated with the simultaneous increases in average lifespan, so this is really a self-correcting problem.

Evolution is a process that is always at work in all circumstances, not something that we can circumvent.

Humans and dolphins. None of the "whales" mentioned (orcas and pilot whales) are actually whales, they're both dolphins.

Technically, they are members of Odontoceti, the "Toothed Whales", which include dolphins. See http://en.wikipedia.org/wiki/Odontoceti

They're members of the delphinidae family (ocean dolphins), which are a member of odontoceti.

Dolphins aren't whales?

Dolphins belong to suborder Odontoceti, which is a whale suborder. So yes, Dolphins are whales.

However, in common naming, people generally call things in the Delphinidae family "Dolphins" and whales not in that family "Whales." Orcas are an exception to this pattern, they're in the family Delphinidae but are called whales.

Dolphins are whales like humans are apes.

Although you will probably just get confusion by speaking of dolphins as a subset of the whale taxon, and not bristling at the thought by a majority of Americans like you would the human/ape relationship.

This kind of response is part of why hackers have such a difficult time in social groups. That it is upvoted 7 times really drives the point home. The article isn't at all about whale nomenclature. It's about an observation of the world around us and a discovery that may explain it.

Yet, this comment has nothing to do with that discovery and only "nitpicks" some superficial detail wholey irrelevant to the discussion. It throws everyone off track with something that doesn't matter -- at all.

It's a semantic debate and it detracts from the conversation. It's annoying and it's why "normals" don't like to talk with hackers.

For the record, some people believe dolphins are whales, and some don't:

http://www.ftexploring.com/askdrg/askdrgalapagos4.html

I agree, but the article didn't contain any actual research figures, just a few suppositions (which made the inaccuracy stand out).

Okiedoke. I wasn't doing anything except throwing an interesting tidbit out there. Personally, I find the whale/dolphin distinction (or lack thereof) fairly interesting. So I shared it. Your comment added more interesting information to the mix. I believe this sharing of information that is related to the post is what comments are for, and I think it's a worthy use of them.

It's especially what threaded comments are for. See, I can't derail a whole conversation-- I can just lead a small subthread away from the main flow. So, I figured this was an OK comment to post on Hacker News.

How can this be right? I know that elephants society is formed around matriarchs that may be quite old.

Based on both the article data and your data I can deduce that old matriarch elephants are still fertile.

Good point, but I'm curious: Are the old matriarchs still able to reproduce, or are they infertile, and have they been infertile for many decades?

And after that question, I think the point of the article was really to look at the abnormalities of animals living past their age of being biologically useful. Biology 101 says, the point of life is to reproduce. So, if an animal lives past the age when it can no longer reproduce, does it still have a biological purpose? If there is such a purpose, is it normal to live long past the age of infertility, or is this just enjoyed by a select few species? And if there's time, why do only a few animals enjoy this benefit? Does forgetting a single species amongst thousands change the purpose of this article?

A couple more reference links on the topic:

http://www.fightaging.org/archives/2009/02/why-are-humans-lo...

http://www.fightaging.org/archives/2005/04/evolution-longe-1...

Evolutionary histories and their effects on life span are still a rich area for research. New and interesting theories are still being developed. For example, see the recent thoughts on crowding as a path to longevity in some species:

http://www.fightaging.org/archives/2008/01/ouroboros-on-the-...

Because Scientific American forgets about elephants?

This is a relatively recent development in human life. Roman women didn't usually live past 30. And it wasn't until the XX century that average life expectancy exceeded 40 years.

EDIT: And 50% of Roman women died giving birth. So there weren't many grandmothers around.

This is a common misconception caused by quoting mean life expectancy at birth, when the distribution is highly asymmetrical. High infant death rates cause low life expectancy at birth, but the life expectancy if you live to age 5 can be massively longer.

A 5 year old ancient Roman was expected to live to 48. About 35% of the ancient Roman population was over 30 years old. The highest listed age is 76, which is the life expectancy of a 70 year old, an age that about 1 in 50 ancient Romans achieved. http://www.utexas.edu/depts/classics/documents/Life.html

http://en.wikipedia.org/wiki/Life_expectancy#The_Popular_Mis...

Excellent point. But that still doesn't leave many grandmothers around (1 in 3 at best?). And they didn't have many years beyond their reproductive age.

Um, think about your numbers a bit more. 1 in 3 what? If 1/3 of the population was over 30 and the average lifespan of people living past infancy was 48, there were probably a lot of grandmothers around. Especially if women were having their first children in their late teens, which is just a guess but seems likely.

Do you have any citation for the statistic you edit to add?

The best I can find in a quick search is that maternal mortality in ancient Rome was about 10-15 per 1000 (http://books.google.com/books?id=6BOQZirLCWgC&pg=PA335&#...). I don't know the average number of pregnancies per woman, but 50% total mortality seems at odds with this.

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