[the5thforce (OP)]

what if early humans/cavemen learned to have sex without thrusting? assuming they had lots of free time to explore eachothers bodies without words before language was invented, perhaps they simply inserted the penis into the vagina and then manually stimulated the clitoris which slowly triggers her pelvic floor muscles on his stationary penis, pelvic floor muscles would oscillate pressure/squeezing the stationary inserted penis until thrusting is almost required in order to prevent slipping out, perhaps the entire thrusting mechanics of sex was primarily an animal technique and early humans adopted a different method but somehow forgot and so reverted to mimicking animals again..
 
if thrusting particularly at the beginning of sex typically hurts human females(many describe a puncture sensation until fully aroused), i have to assume it wouldnt have been a very fertile technique for early humans- especially considering females were much more robust(neanderthal females for example- you wouldnt want to upset one), also keep in mind thrusting is unnecessary for triggering male orgasm- oscillating pressure is vastly more important(combining pressure with thrusting only speeds up the process)

instead of early humans training the vagina to stay loose for thrusting, the female might instead have contracted her pelvic floor muscles until thrusting was necessary, perhaps learning to oscillate pressure to the cadence of clitoral stimulation, you might even venture to say this process couldve played a vital role in the development of early language- humans training themselves to associate vocal sounds with sexual contractions indicating good or bad which is ultimately the basis of language. if what i just proposed at all played a factor in human evolution it would be highly ironic that we lost these techniques in translation over the 200,000+ years humans have been around..

[the5thforce (OP)]

ultimately theres room for many potentially 'fertile' techniques- be it violent coercion, mutual desire to please, or mutual desire to procreate- likely a mix of all three have been around for a very long time. i was only trying to imagine how it wouldve played out before language was invented and before human females lost so much of their muscle mass which i believe didnt happen until relatively recently on an evolutionary scale. i imagine if sex was too undesireable for the female and obviously raising children is incredibly taxing on resources we likely would not have survived as long as we have


in response to a few points on the recent podcast "Rules of Attraction: The Science of Sex"
http://www.thenakedscientists.com/HTML/typo3conf/ext/naksci_podcast/jplayer/player.php?podcast=1001299

structural beauty:

genders evolved because of radioactively decaying DNA, genders survive because of the genetic recycling a dual-gender system provides which counters DNA decay while protecting desireable traits

male muscular-skeletal robusticity protects the dna which then serves to renew the structural dna of female offspring, the female protects and improves the appearance of the male dna through sexual selection

an asexual/hermaphroditic genetic-cloning system is unsustainable long term as the genome eventually succumbs to radioactively induced infertility/disease, which is why so few genetically-complex organisms survive in such systems

in most species a healthy female is designed to seek the most robust male to ensure offspring inherit dna that is structurally viable, and the male is designed to seek the most aesthetic/youthful/proportional female to ensure their offspring are sexually viable

[evan_au]

what if early humans/cavemen learned to have sex without thrusting?

The evolutionary biologists among us suggest that thrusting is effective at flushing out any semen from previous matings (this is not just restricted to humans).
They suggest that it is a hard-wired instinct for a male to improve his odds of fathering a child.
The thrusting instinct stops at ejaculation.

[the5thforce (OP)]

what if early humans/cavemen learned to have sex without thrusting?

The evolutionary biologists among us suggest that thrusting is effective at flushing out any semen from previous matings (this is not just restricted to humans).
They suggest that it is a hard-wired instinct for a male to improve his odds of fathering a child.
The thrusting instinct stops at ejaculation.

thats possible, but considering that it takes more than 2 children per woman to sustain the population, eventually you'd be fathering multiple viable children with the woman youre mating with regardless of which ones are actually yours, also my original point was that humans for whatever reasons required so much more intelligence to survive- i believe our sexuality(and the need to get creative to persuade women to have more than 2 children without using language) couldve played a significant role

[tkadm30]

Is there any evolutionary purpose to anal or oral sex?

[chris]

Bonding and trust, I would think. These are non-procreative acts but they nevertheless, I would speculate, lead to closeness and increased odds of a relationship enduring, which increases the chance of reproduction.

[alancalverd]

There's no primary reproductive purpose to holding hands, kissing, or even looking at one another, but whilst most  species operate on the F&F principle, human babies take a long time to reach any sort of independence so there seems to be some evolutionary advantage in pair bonding and this is enhanced by all sorts of exchanges.

[alancalverd]

perhaps the entire thrusting mechanics of sex was primarily an animal technique and early humans adopted a different method but somehow forgot and so reverted to mimicking animals again..

Never forget that homo sapiens is an animal. The evolution of face-to-face sex is, however, unusual among vertebrates and is almost certainly a very recent phenomenon.

[Bored chemist]

Is there any evolutionary purpose to anal or oral sex?

There's no obvious evolutionary advantage to music. My best guess is that it's an incidental effect of something which is important- perhaps our "pattern spotting" ability.

We gain evolutionary advantage from recognising patterns in the world, so we evolved to like spotting patters.
Music lets us do that, so we like  music.

In the same way, we evolved to like having sex (because any of our ancestors who didn't, didn't become ancestors of anyone).
And we like it so much that we keep doing it in every way we can.

[syhprum]

All pornography emphasise of the importance of abnormally large peens if they gave an evolutionary advantage they would all be larger than what they are.
I would seem that they would be useful to remove the sperm from a previous insemination but this seems to have had little effect on evolution   

[alancalverd]

On further thought, it's odd that the fundamental process of adding sperm to ovum evolved in the first place, and that having done so it appears in so many different mechanisms from wind-blown pollination to copulation, whilst (as evidenced by bacteria and amoebae) it isn't really necessary at all!

[nekS576]

This is quite a controversial topic for conversation, but one thing can be said, what is acceptable for two - should not be discussed

[Petrochemicals]

The hidden psycology of sex, the instinctive mating urge, attractiveness, social belonging etc are all things people are partially blind too and govern us and our outlooks in ways we struggle to guage.

As stephen Fry put it "the urge to fill a snug hole" makes no sense, so anything else is probably going to be just as rational.

[syhprum]

"Is there any evolutionary purpose to anal or oral sex? "

The ingestion of seminal fluid is said to be an aid to giving birth this may be part of the reason for oral sex.