Do you have calluses on your feet? Don't fear them, though. New research has revealed that foot calluses — thickened skin that forms naturally when one walks barefoot — have evolved to protect the feet and provide for comfortable walking in perhaps ways that shoes can't match.

你腳上有繭嗎？不要怕它們。新的研究表明，腳繭作為一種赤腳行走時自然形成的厚皮，可以讓我們的行走更加舒適，還能起到保護腳的作用。某種程度上來說，穿鞋子都達不到這樣的效果呢。

Unlike shoes, foot calluses offer protection without compromising sensitivity or gait, according to a study published in June online in the journal Nature. Shoes, in contrast, reduce sensitivity in the foot and alter the way that the impact forces transfer from the foot to joints higher up the leg.

《自然》雜志6月在線發(fā)布的一項研究表明，與鞋子不同的是，腳繭提供的保護并不會影響腳部的敏感度和步態(tài)。相比之下，鞋子會降低腳部的敏感度，并會改變從腳部傳遞到腿部上方關節(jié)所受到的沖擊力。

The researchers — from institutes in the United States, Germany and Africa — stressed that their findings don't demonstrate that walking barefoot is healthier than walking in shoes. At its core, the study is about human evolution.

來自美國、德國和非洲研究機構的專家強調，他們的發(fā)現(xiàn)并不能證明赤腳行走比穿鞋走路更健康。這項研究的核心是人類進化。

Yet the fact that we have evolved to walk barefoot, and that barefoot walking is mechanically different from walking in shoes, may imply that going barefoot can impart certain long-term health benefits worth investigating, the researchers said.

但研究人員說，人類一路進化到能夠赤腳行走，并且它和穿鞋行走從物理上來說是不同的，這個事實可能意味著赤腳行走對健康有長期效益，值得人們研究。

"It is fun to figure out how our bodies evolved to function," said Daniel Lieberman, professor of human evolutionary biology at Harvard University, who co-led the study. "The sensory benefits of being barefoot might have health implications, but these need to be studied."

這項研究的帶頭人之一，哈佛大學人類進化生物學教授丹尼爾·利伯曼說：“研究人體功能如何進化很有趣。赤腳行走所帶來的感官益處可能會促進健康，但還需要進一步研究?！?/p>

For most of human's 200,000-year existence, we walked barefoot. The oldest discovered footwear dates to about 8,000 years ago, although there is indirect evidence of sandals and moccasins tens of thousands of years before this, the researchers said. Cushioned shoes are even more recent — only about 300 years old.

在人類20萬年進化史的大部分時間里，我們都赤足走路。研究人員說，最早發(fā)現(xiàn)的鞋可以追溯到大約8000年前，盡管在這之前的數(shù)萬年里，有間接證據(jù)表明涼鞋和鹿皮鞋的存在。軟底鞋是最近才出現(xiàn)的——只有大約300年的歷史。

Because calluses are the evolutionary solution to protecting the foot, Lieberman's team set out to assess how these formations might differ from shoes in maintaining grounding and comfort. Their study examined the foot calluses of more than 100 adults, the majority from Kenya. About half of the subjects walked barefoot most of the time, and half mostly wore shoes.

因為老繭是保護腳部而進化出的功能，利伯曼的團隊開始評估它在保持腳底舒適度方面與鞋子的不同之處。他們檢測了100多名成年人的腳繭，其中大多數(shù)來自肯尼亞。大約一半的受試者大部分時間都是赤腳行走，一半的受試者主要穿著鞋子。

Among the barefoot walkers, the thickness of the calluses did not dampen tactile sensitivity, or the ability of the foot to feel the sensation of the ground while walking. Shoes, with their cushioned bottoms, clearly mute this sensation.

在赤腳行走的人當中，老繭的厚度并不會降低觸覺的敏感性，也不會降低步行時腳部對地面的感知力，而軟底鞋明顯地減弱了這種感覺。

However, very thick calluses don't simply act like shoe cushions. The callus thickness can protect against heat or sharp objects, providing comfort and safety, like shoes can. But the sensory receptors in the foot that detect ground surface differences still transmit signals to the brain.

然而，厚老繭并不像鞋底一樣簡單地起到緩沖作用。繭的厚度可以防止高溫或尖銳的物體，就像鞋子一樣提供舒適和安全。但是，腳內檢測地面差異的感覺受體仍然會向大腦發(fā)送信號。

This uninhibited signal — that sensation of feeling the earth — may help the barefoot walker keep balance, strengthen muscles and create a stronger neural connections between the feet and the brain.

這種不受抑制的信號，即對地面的感知力，可能有助于赤腳行走的人保持平衡，增強肌肉，并在腳和大腦之間建立更強大的神經連接。

"We suggest children to walk barefoot on humid grass with the purpose to stimulate the afferents (nerves traveling to the brain) for developmental reasons," said Thomas Milani, a professorship of human locomotion at the Technische Universit?t Chemnitz in Germany, who co-led the study.

這項研究的帶頭人之一，德國切姆尼茨理工大學的人類運動教授托馬斯·米蘭尼說：“我們建議兒童光腳走在潮濕的草地上，這樣可以刺激大腦的傳入神經（傳到大腦的神經），有利于發(fā)育?！?/p>

The researchers also found that walking in shoes softens the initial impact of the footstep but ultimately delivers more force to the joints compared with what is seen in thick-callused individuals. This, too, may have health implications for the knees and hips, something that should be studied, the researchers said.

研究人員還發(fā)現(xiàn)，穿鞋行走可以減輕腳部受到的最初沖擊，但與有厚繭的個體相比較，它最終會將更大的力傳遞到關節(jié)上。研究人員說，這也可能對膝蓋和臀部的健康產生影響，這一點值得研究。

Paul Zehr, a professor of kinesiology and neuroscience at the University of Victoria, British Columbia, Canada, added that one of the study's limitations is that tactile sensitivity was assessed at rest, with a device that sent vibrations into the sole, and so these results may not necessarily hold true for walking.

加拿大不列顛哥倫比亞省維多利亞大學運動生理學和神經科學教授E.Paul Zehr補充說，這項研究的局限性之一是，觸覺敏感度是在休息時進行評估的，用的是一種能向足底發(fā)出振動的設備，所以這些結果可能并不一定適用于走路。

Barefoot walking isn't the best idea for everyone, despite its evolutionary basis. People with diabetes and peripheral neuropathy can wound their feet and not realize it. Lieberman's team would like to investigate the practicality of wearing thin sandals or moccasins, which might allow for a lot of tactile stimulation compared to cushioned shoes but offer added protection from abrasions.

赤腳走路盡管有進化理論基礎的支撐，但它也并非有利于所有人。患有糖尿病和周圍神經病變的人，可能因為赤足走路傷到腳而不自知。利伯曼的研究小組希望研究穿薄涼鞋或軟皮鞋的實用性，與軟底鞋相比，這可能會帶來很多觸覺刺激，但可以提供額外的防磨損保護。

Editor: Shang Zhen

Intern: Hu Sile