약지 긴 남자, 매력 넘치는데 ‘체력’도 강하다 Distance running may be an evolutionary ‘signal’ for desirable male genes

英 연구팀, 손가락 길이와 마라톤 성적 비교

평균 24분 33초 더 빨라

약지가 검지보다 긴 사람(왼쪽)은 검지가 긴 사람에 비해(오른쪽) 태아 시절 테스토스테론에 많이 노출됐으며, 

오래달리기에도 강한 것으로 밝혀졌다. - Danny Longman 교수 제공

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케이콘텐츠 

 

건강한 남편감이나 사윗감을 한눈에 알아보려면 손가락을 살펴봐야 할까. 영국 연구진이 약지 길이가 길면 실제로 체력도 강하다는 연구 결과를 발표했다.   롱맨 대디 케임브리지대 생물인류학부 교수팀은 마라톤에 참가한 선수들의 손가락 길이를 연구한 결과, 약지가 긴 선수들이 전반적으로 성적이 더 뛰어나다는 사실을 밝혀내 미국 ‘과학공공도서관저널(PLOS ONE)’ 8일자에 게재했다. 연구팀은 영국 노팅엄에서 열린 ‘2013 로빗훗 하프마라톤’에 참가한 선수 542명의 손가락 길이와 대회 완주 성적을 비교했다.   그 결과 약지가 검지에 비해 긴 비율이 상위 10% 안에 들어가는 남성은 그렇지 않은 남성에 비해 평균 24분 33초 기록이 더 빨랐다. 마라톤 경기가 2~3시간 정도 진행되는 점을 고려하면 20% 가까이 기록 차이를 보인 셈이다.   여성의 경우도 동일한 결과를 보였지만 남자보다는 차이가 작았다. 약지가 검지에 빈 여성은 평균 11분 59초 빨리 완주했다. 남녀 모두 약지가 길수록 오래달리기를 잘했지만 남성에게서 더 두드러진 셈이다.   연구팀은 그 원인으로 성호르몬을 주목했다. 약지와 검지의 길이가 달라지는 까닭은 임신 초기에 결정된다는 사실은 여러 연구결과를 통해 정설로 받아들여지고 있다. 이는 임신 13주 이내에 결정되는 것으로 약지는 남성 호르몬인 테스토스테론의 영향을 받고, 검지는 여성 호르몬인 에스트로겐의 영향을 받는다. 어머니의 호르몬 농도가 아이의 손가락 길이에 영향을 미치는 셈이다.   테스토스테론에 노출이 많이 돼 약지가 긴 사람일수록 여성에게 부드러운 행동을 보이고, 매력적인 얼굴로 인식되는 경향이 강했다. 또 리더십이 강하며 심지어는 정자수가 많고 생식기가 더 길다는 연구결과도 있다.   연구팀은 이  연구결과를 수렵생활을 했던 조상들의 생활 습관에서 기인한 것으로 보고 있다. 아프리카와 멕시코 원주민에서 지금도 확인되듯이 사냥은 동물을 장시간 쫓아가야 한다. 남성호르몬에 노출될수록 신체는 장시간 달리기를 하도록 진화했다는 것이다.   롱맨 교수는 “태아 때 남성호르몬에 더 많이 노출될수록 오래달리기를 비롯해 지구력에 영향을 미치는 것이 사실“이라며 “훈련처럼 큰 영향을 미친다고는 볼 수 없지만 손가락 비율과 지구력은 분명히 상관관계가 있다”고 말했다.   당신의 손가락 비율은?   위키미디어 제공 손가락 길이는 오른쪽 사진처럼 아래쪽 마디가 시작되는 지점부터 측정하면 된다. 검지의 길이를 약지의 길이로 나눴을 때 나오는 값을 기준으로 삼는다. 2005년 베일리 허드 캐나다 앨버타대 심리학부 교수팀은 평균값이 남성의 경우 0.947, 여성은 0.965라고 밝혔다. 남성의 경우 손가락 비율이 이보다 짧으면 이성에게 충분히 남성다운 매력을 어필할 수 있는 사람이라는 뜻이다. 한편 이 값이 너무 작은 사람은 주의렵결핍과잉행동장애(ADHD)나 자폐증 위험이 크다는 연구결과도 있다. 권예슬 기자 yskwon@donga.com

 

New research shows that males with higher ‘reproductive potential’ 

are better distance runners. This may have been used by females 

as a reliable signal of high male genetic quality during our hunter-

gatherer past, as good runners are more likely to have other traits 

of good hunters and providers, such as intelligence and generosity.

Pre-birth exposure to high levels of the male sex hormone testosterone has already been shown to confer evolutionary advantages for men: strength of sex drive, sperm count, cardiovascular efficiency and spatial awareness, for example.  Now, latest research on marathon runners using finger length as a marker for hormone exposure shows that people who experienced higher testosterone in the womb are also better at distance running – a correlation particularly strong in men, although also present in women. Researchers say the finding that males with greater “reproductive potential” from an evolutionary standpoint are better distance runners suggests females may have selected for such athletic endurance when mating during our hunter-gatherer past, perhaps because ‘persistence hunting’ – exhausting prey by tirelessly tracking it – was a vital way to get food. Distance running may also have acted as a positive ‘signal’ for females of desirable male genetics more generally, say researchers: good runners were likely to be better persistence hunters and consequently better providers. This increases the likelihood they would have other key traits of good providers such as intelligence and generosity. The study was conducted by researchers at the University of Cambridge’s Division of Biological Anthropology and is published today in the journal PLOS ONE. “The observation that endurance running ability is connected to reproductive potential in men suggests that women in our hunter-gatherer past were able to observe running as a signal for a good breeding partner,” said the study’s lead author Dr Danny Longman.      “It was thought that a better hunter would have got more meat, and had a healthier – and larger – family as a consequence of providing more meat for his family. But hunter-gatherers may have used egalitarian systems with equal meat distribution as we see in remaining tribes today. In which case more meat is not a factor, but the ability to get meat would signal underlying traits of athletic endurance, as well as intelligence – to track and outwit prey – and generosity – to contribute to tribal society. All traits you want passed on to your children,” he said.  Using the largest sample of marathon runners of any study of its kind, Longman and colleagues tested for specific finger lengths known as the 2D:4D digit ratio. Previous studies have showed that those exposed to more prenatal testosterone have a longer ring finger (4th digit) in comparison to their index finger (2nd digit).  This digit ratio is the most accurate known way to tell if an adult was exposed to higher levels of testosterone as a foetus – a proven predictor of the “potential for reproductive success” in men, say researchers.  The team analysed 542 runners (439 men; 103 women) at the Robin Hood half marathon in Nottingham by photocopying hands and taking run times and other key details just after runners crossed the line. They found that the 10% of men with the most masculine digit ratios were, on average, 24 minutes and 33 seconds faster than the 10% of men with the least masculine digit ratios. The correlation was also found in women, but was much more pronounced in men, suggesting a stronger evolutionary selection in men for running ability. The 10% of women with the most masculine digit ratios were, on average, 11 minutes and 59 seconds faster than the 10% with the least masculine. Longman points out that prenatal testosterone exposure is a very small influence on running ability that doesn’t compete with training and muscle strength when it comes to performance, but their unprecedentedly large sample size of over 500 people enabled the team to gather conclusive evidence. “Humans are hopeless sprinters. Rabbits, for example, are much faster sprinters, despite being fat and round. But humans are fantastically efficient long-distance runners, comparable to wolves and wild coyotes,” said Longman. “We sweat when most animals would overheat; our tendons and posture are designed to propel our next strides – there was likely a selective pressure for all these benefits during our evolution.” Persistence hunting is thought to have been one of the earliest forms of human hunting, evolving approximately two million years ago, said Longman. “You can still see examples of persistence hunting in parts of Africa and Mexico today. Hunters will deliberately choose the hottest time of day to hunt, and chase and track an antelope or gnu over 30 to 40 kilometres for four or five hours. The animal recovers less and less from its running until it collapses exhausted and is easy to kill,” Longman said. “This may sound crazy, but when a hunter is relatively fit the amount of energy they expend is actually tiny compared to the energy benefits of an antelope-sized animal, for example. Before the domestication of dogs, persistence hunting may have been one of the most efficient forms of hunting, and as a consequence may have shaped human evolution.” https://www.cam.ac.uk/research/news/distance-running-may-be-an-evolutionary-signal-for-desirable-male-genes

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