Natural Selection: Survival of the Most Likely to Get Pregnant as a Teenager

If I am understanding this study correctly, its talking about how some teens have a genetic predisposition to get pregnant early. It also deals with "reproductive fitness," which isn't so much a biological quality in the teens themselves but in the number of children they have over a lifetime. A person with a high reproductive fitness quality would have more children than someone with a low reproductive quality. I should have been a biologist.

The study was published in 2001, so its a little old but it says that education level, religion and culture all play a part in determining if a teenager gets pregnant. It also shows that genetics have a say in the matter. The study repeated the fact that women with a higher level of education tender to have fewer children and have them later in life, while less educated women have more kids earlier. (That's something I've noticed. My high school pals all went to college. One of them has two kids, and that's because they were twins. A former co-worker didn't go beyond high school and she has four kids. My co-worker is 31, the youngest of my pals is 29.) University educated women had a 35% lower reproductive quality than those that left school ASAP.

Religion also played a part, with Roman Catholics have a 20% higher reproductive fitness than other religions. However, take away all of the religious, educational and social factors and genetics still have an effect. Genes seems to partly decide when a girl starts puberty, has their first baby and begins menopause. This shows Darwinian evolution in action. Women with the gene for early puberty will outnumber those that don't, giving that gene a better chance of survival.

The study was conducted by observing the birth rates of 2,710 pairs of female twins. Even after we controlled for social factors, there was still lots of genetically heritable genetic variation in the life history traits - this is a really unexpected finding," says Dr Ian Owens, a professor at Imperial College's Biology and Biochemistry Department. "Looking to the future, I would expect to pick up genetic changes within the ten generations since industrialisation."

Source:
http://news.bbc.co.uk/2/hi/health/1292228.stm