Navigation Links
Low testosterone level in Amazonian tribe responds to competition

Santa Barbara, Calif. As part of an isolated indigenous group in central Bolivia, Tsimane men spend much of their time hunting, foraging, fishing, and clearing land by hand to grow crops. Their ability to maintain the physical activity required to survive each day might imply they have higher than average male testosterone levels.

Anthropologists at UC Santa Barbara and the University of Washington have found, however, that the baseline testosterone level of Tsimane men is 33 percent lower than that of men living in the United States, where life is physically less demanding. Also, in contrast to men in the U.S., the Bolivian foragers-farmers do not show declines in testosterone as they age. The researchers' findings appear today in the Proceedings of the Royal Society B.

According to Michael Gurven, the lives of the Tsimane offer a glimpse of how humans survived before industrialization and modern amenities. "Our lifestyle is now an anomaly, a major departure from our species' long-term existence as hunter-gatherers," said Gurven, professor of anthropology at UCSB and co-author of the paper. Gurven is also co-director of the Tsimane Health and Life History Project, a collaboration between UCSB and the University of New Mexico.

"Maintaining high levels of testosterone compromises the immune system, so it makes sense to keep it low in environments where parasites and pathogens are rampant, as they are where the Tsimane live," said Ben Trumble, a graduate student in anthropology at the University of Washington, and the paper's lead author.

That men living in the U.S. have greater levels of circulating testosterone represents an "evolutionarily novel spike," Trumble continued. The spike reflects how low levels of pathogens and parasites in the U.S. and other industrialized countries allow men to maintain higher testosterone levels without risk of infection. He also pointed out that while men in the U.S. show a decline in testosterone as they age, and the drop serves as a sentinel for age-related disease, Tsimane men maintain a stable testosterone level across their lifespan, and show little incidence of obesity, heart disease, and other illnesses associated with older age.

Despite lower levels of circulating testosterone under normal conditions, the forager-farmers do have something in common with U.S. men short-term spikes of testosterone during competition.

The researchers organized a soccer tournament for eight Tsimane teams, and discovered that Tsimane men experienced a 30 percent increase in testosterone immediately after a soccer game. An hour after the game, testosterone was still 15 percent higher than under normal conditions. Similar increases have been shown in men living in the U.S. or other industrialized countries following, sports competitions.

The study suggests that competition-linked bursts of testosterone are a fundamental aspect of human biology that persists even if it increases risk of sickness or infection. "What's interesting is that in spite of being in a more pathogenic environment, it's still important to raise testosterone for short-bursts of energy and competition," Gurven said.

As to whether higher levels of the male hormone would offer a competitive advantage in sports, Trumble suspects that because U.S. men are "taller and weigh more than Tsimane men, and tend to be exposed to fewer parasites and pathogens, they would probably have a competitive advantage, regardless of circulating testosterone."

Contact: Andrea Estrada
University of California - Santa Barbara

Related medicine news :

1. Too Much Testosterone Linked to Inflated Ego: Study
2. Testosterone Exposure May Explain Boys Language Delay
3. Hanging with the boys - female Alpine marmots benefit from a bit of pre-natal testosterone
4. For Older Men, Lowered Testosterone May Mean Muscle Loss
5. Older men with higher testosterone levels lose less muscle mass as they age
6. Research Suggests Penis Might Produce Testosterone
7. Testosterone Levels Seem to Fall With Fatherhood
8. BUSM: Testosterone deficiency and replacement therapy in men
9. Low testosterone linked to varicoceles
10. Surgery-related weight loss in men reverses testosterone deficiency
11. Study suggests another look at testosterone-prostate cancer link
Post Your Comments:
Related Image:
Low testosterone level in Amazonian tribe responds to competition
(Date:12/1/2015)... ... ... Lutronic, a leading innovator of aesthetic and medical laser and energy-based technology, ... in the United States. Clarity is a Superior Dual Wavelength Platform which combines ... single platform that is easy to own and operate. , For over a ...
(Date:12/1/2015)... ... December 01, 2015 , ... PartnerTech ... through membership and leadership since 2008. Gary Bruce, President of PartnerTech North America, ... has spent a significant amount of time in Sweden since joining PartnerTech based ...
(Date:12/1/2015)... ... 01, 2015 , ... SonaCare Medical congratulates the University College ... Award on November 18th. This prestigious award recognizes annually organizations that cultivate truly ... the medical landscape. , The UCLH team won the award for their innovative ...
(Date:11/30/2015)... ... ... Trevor and Taylor Crabb have unveiled an exciting new campaign to ... United States. This hybrid crowdfunding campaign is designed to provide the Crabb ... to offering corporate sponsors with some great marketing deliverables with the brothers for the ...
(Date:11/30/2015)... ... December 01, 2015 , ... ... as a 2015-2016 inductee into its VIP Woman of the Year Circle. ... the nation’s leading networking organization exclusively for professional women, boasting 850,000 members and ...
Breaking Medicine News(10 mins):
(Date:12/1/2015)... Russia has always been a country of ... registered in Europe in 2015 were tested in ... Russia has always been a country of choice for global ... Europe in 2015 were tested in phase II-III ... has always been a country of choice for global multi-center phase ...
(Date:12/1/2015)... Dec. 01, 2015 ... "Veterinary Equipment and Disposables Market by product, ... report to their offering. --> ... "Veterinary Equipment and Disposables Market by product, by ... to their offering. --> Research and ...
(Date:12/1/2015)... 1, 2015 Contraceptives ... Contraceptives, Male Condoms, Female Condoms, Intrauterine Devices, ... Diaphragms, Contraceptive Sponges, Non-Surgical Permanent Contraception Devices) ... Trends and Forecast 2014 - 2020 ", ... (TMR).The report states that the global contraceptives ...
Breaking Medicine Technology: