Bittersweet Destiny - like I said, is 85% of what I would write myself. I was going to go chapter by chapter (assuming that would mean something to you) but, mostly the parts that are written poorly are those that lacked data (baby brain development)...and i am still thinking about his strong argument that sex (in plants, animals) was driven or kicked off by pathogen pressure.
two things I have always been dragging around with me
female promiscuity and marriage; since humans are 85% polygamous and some bit thereafter monogamous .... I always get the feeling that the female is still treated as "passively" having sex, but usually sex ONLY within monogamous relationships. the book makes a good attempt....but still...
okay
my assumptions are for some form of life before agriculture, say ~200,000 years to then, when Homo sapiens is on the scene.
idea: females take advantage of their security in knowing which offspring is theirs and want TWO things - a strong healthy male (sexual selection causing size dimorphism) AND a provider/caretaker to share the work load (selection for mother aspects in males). There is no reason at all to presume that females need these two to be one in the same. The strategy is still K (few mates) ... I don't also see why a female, even though she is limited to the number of offspring, would only invest in one sperm donor. The male, needs a strategy to ensure that at least some of the offspring that he has, are actually his. This is more telling that simply sperm is cheap and because of that, males want to mate with everyone. This gives are reason for the high sex drive in males. Kind of like fish. More sperm, more chance, and you need to take those chances. The female always knows.
One the flip side, if he (if he is the caretaker version) has to raise a child that is not his own, some of his own children will be born anyway. This is where marriage comes in. It is a compromise on both sides - the males' attempt to control cuckolding and the females chance at trapping a caretaker.
Humans have large penises (in view of primates, from what I learned in my anthropology course), large sperm count; indicative of the polygamous life style - but more importantly, the penis does not evolve like that without direct selection pressure in the vagina, in combating sperm with sperm in the same female at the same time.
(you can find anything, but: http://www.newscientist.com/article/mg18424731.500-sleeping-around-boosts-evolution.html ; http://www.news-medical.net/news/2004/11/08/6147.aspx ; i do have access to the paper, i downloaded it - humans are in the middle.. maybe the numbers are correct, maybe not - but on average)
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Can twins have two different fathers? One in 12 fraternal twin sets have two different fathers worldwide, while in the US the rate is 1 in 400 twinsets.
data: http://www.ncbi.nlm.nih.gov/pubmed/7871943
One 1992 study estimates that the frequency of heteropaternal superfecundation among dizygotic twins whose parents were involved in paternity suits was approximately 2.4%; see the references section, below, for more details.
expand that with the rare probability of that happening: The number of living human twins in the world has been estimated to be approximately 125 million in 2006[1] (roughly 1.9% of the world population), with just 10 million monozygotic twins (roughly 0.2% of the world population and 8% of all twins). The twin birth rate in the United States in 2004, 2005 and 2006 was slightly above 32 twin live births per 1,000 live births[2].
Gwrant:
Amazing, eh? That so many women would have multiple partners slop inside of them at the same time... Obviously I'm on the other end of the spectrum.
I have a hard time imagining how people could regularly achieve that these days. I am utterly dull, apparently.
In a tribal setting 200k years ago, I imagine (letting my non-researched fantasies run amok) the relationships would be looser for two reasons.
One, because teenagers tend to fall in and out of love fairly quickly and the average age of the Ancients was very young. Women (girls) would be as fickle and sentimental as teenagers today. If they survived to adulthood (18+), then they might settle down and behave more "monogamously".
Could you imagine a evolutionary process based on the mentalities of horny teenagers?
Two, in a group of 50 people, 25 are of the same sex and only 10 or so would make suitable partners, a young person does not have a whole lot to choose from. It would be like being born and raised in a small classroom of teenagers. A bunch of f-ing losers except maybe one or two decent catches...
With regards to being a provider- gift giving (care-taking) is highest in the honeymoon period (first few months). Romancing with words, gifts, heroic deeds, etc... After a year or so, the infatuation plummets.
I think boy/men would take care of children or provide for them primarily as a way of looking good for the girls/women. I feel within myself and urge to show-off how fun, kind, and physically fit (throwing kids up in the air) I am with kids when women are around...
Boys/Men are not really trapped (except in the modern legal sense) and I believe harems where much more overtly common (versus the covert commonality the data reveal today).
For a good read, check out Helen Fisher's Anatomy of Love.
It has been a long while since I've read Bittersweet Destiny. I can't remember the arguments specifically.
