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The Evolution of Killer Sperm
Recent DNA studies in the UK and the US have found that up to 9% of men unknowingly raise children that are not biologically their own. In fact, each and every human alive today is a byproduct of the infidelity and cuckoldry of their evolutionary past.
So, how has infidelity and the risk of cuckoldry affected our evolution? Sexual jealousy is an obvious example of a behaviour that we have evolved to counter the risk of infidelity.
But there are other unseen aspects of our biochemistry and physiology that have been directly influenced by the promiscuity of our distant ancestors. When considering that evolution has affected every single aspect of our biological make up, from head to toe, one must not disregard the Human penis and how and why it has evolved to be the way it is.
The Human penis is a classic product of evolution. It has evolved to combat female infidelity while simultaneously assuring successful insemination. Infidelity has had the greatest influence on the shape and size of the penis, the type of sperm, viscosity of semen and even the thrusting of the penis during sex.
Human females are not much different to their primate sisters - they are highly prone to infidelity. Our closest primate cousin is the chimpanzee. During their estrous phase, or the peak in their fertility cycle, female chimps will have sex about 50 times a day with a couple of dozen males.
Female chimps have evolved to become so promiscuous because the survival of the fittest chimp has evolved to become the survival of the fittest sperm. During the peak in a female chimp's fertility, literally billions of sperm of rival males are at war in her vagina.
And at war they are. Less than 1% of a primate's sperm, including humans, is designed to actually fertilize the egg. The remaining sperm is equally divided between "blocker" sperm and "killer," or "Kamikaze," sperm.
Blocker sperm comes in many shapes and sizes. It quite often has a large head, and sometimes has even with more than one head. Blocker sperm groups together in the ducts of the cervix, halting any rival sperm from traversing through to the fallopian tubes.
Killer sperm has evolved a "search and destroy" function. Each killer sperm has a head full of enough poison to kill many rival sperm. A killer sperm swims around, seeking out rival sperm by "nudging" each sperm it comes across, essentially sniffing out rival sperm.
When a rival sperm is found, the tip of the killer sperm injects its rival with poison and moves on. Given that a human male can ejaculate up to 600 million sperm in one hit, that one blast of ejaculate has enough killer sperm to kill well over a billion rival sperm cells.
In addition to blocker and killer sperm, human seminal fluid has evolved to become one of the stickiest of primate ejaculate. Semenogelin is a sticky protein that allows ejaculated semen to form a gluey plug, that simultaneously helps semen remain in the vaginal tract while also acting as a barrier to prevent rival sperm from traversing through the cervical ducts.
Survival of the fittest is thus shown to be fought right at the very "front line" of conception and has even affected the make up of human semen.
About the Author Tanya Zafino has written an Ebook about acne treatment. Go to http://www.thezafinomethod.com/
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