長い間水の中にいると手足の指にたくさん「しわ」ができる。このしわを見たことがない人はいないだろう。私はこれまで、このしわは単に皮膚が水分を吸収し膨らんでできたもので、何の役割もないと思っていた。ところが、①そうではないという記事を読んだ。滑り止めの役割を果たしているというのだ。
この記事は、ある論文の実験結果をもとに書かれていた。②実験は次のように行われた。ひとつの容器に小さなガラス玉を入れ、それを指でつかんで別の容器に移し替えるのにかかる時間を計る。ガラス玉が入っている容器には、水入りのものと水なしのものが準備された。また、手はしわがある状態とない状態で、それぞれのかかる時間が計測された。しわは、ぬるま湯に手を浸すことで発生させた。結果は次のようなものである。
まず水の有無について見てみると、水入りの容器から移し替えるより、水なしの容器から移し替えるほうが速い。次に水入り、水なしの各条件において、しわの有無の違いによる結果を見てみると、水なしの場合、しわがあってもなくても大した差はない。しかし、水入りの場合、しわがあるほうが速い。以上の結果から、実験者は、しわは水中などぬれた環境で物をつかみやすくするためにできるようになった可能性があると述べているそうだ。
しかし、どうなのだろうか。滑り止めのためであれば、水に入れたらすぐにしわができないとおかしいのではないだろうか。しわの役割を知るためには、新たな実験を待たなければならない。
AI translation, cross-checked between two models.
When we stay in water for a long time, many “wrinkles” form on our fingers and toes. There is probably no one who has never seen these wrinkles. Until now, I had thought that these wrinkles were simply caused by the skin absorbing water and swelling, and that they served no purpose. However, I read an article saying that ① this is not the case. According to the article, they serve to prevent slipping.
The article was written based on the results of an experiment reported in a research paper. ② The experiment was conducted as follows. Small glass beads were placed in one container, and the time required to pick them up with the fingers and transfer them to another container was measured. Two versions of the container holding the glass beads were prepared: one with water and one without. The time taken was also measured separately with the hands in a wrinkled state and in a non-wrinkled state. The wrinkles were produced by soaking the hands in lukewarm water. The results were as follows.
First, looking at the presence or absence of water, transferring the beads from the container without water was faster than transferring them from the container with water. Next, when the results for wrinkled and non-wrinkled hands were compared under each of the wet and dry conditions, there was no significant difference in the dry condition, whether the hands were wrinkled or not. In the wet condition, however, the wrinkled hands were faster. Based on these results, the experimenter reportedly stated that wrinkles may have developed to make it easier to grip objects in wet environments such as underwater.
But is that really the case? If their purpose is to prevent slipping, shouldn't the wrinkles appear as soon as the hands enter the water? To determine the role of these wrinkles, we will have to wait for further experiments.
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