Research press release


Communications Biology

Zoology: Numerical abilities may be hardwired in newly-hatched zebrafish

孵化後96時間以内のゼブラフィッシュ(Dania rerio)の幼生が、黒い線の本数の違いを識別したことを報告する論文が、Communications Biologyに掲載される。孵化直後のゼブラフィッシュに数的能力が組み込まれているという可能性が、今回の知見から示唆されている。


今回、Tyrone Lucon-Xiccatoたちは、孵化して間もないゼブラフィッシュの幼生が、水槽の白い壁に印刷された黒い縦線の本数の違いを識別できるかどうかを調べた。これらの幼生は、最初に壁面が黒い縦線の模様で覆われた水槽で飼育された。それから96時間後に180匹の幼生が別の水槽の中央部に移された。この水槽の2つの壁面は白地に最大4本の黒い線が印刷されていた。この実験で、幼生が黒い線の本数の多い壁面に泳いでいくのか、少ない壁面に泳いでいくのか、あるいは水槽の中央部に留まるのかを観察し、それぞれの区画に滞留していた時間を計測した。そして、120匹の幼生を用いた対照試験では、縦線の密度、表面積と縦線によって形成された全体の形状の違いを制御して同じ実験が実施された。



Zebrafish (Dania rerio) larvae can recognise differences between numbers of black bars within 96 hours of hatching, according to a study published in Communications Biology. The findings suggest that numerical abilities may be hardwired in newly-hatched zebrafish, according to the authors.

Previous research has demonstrated numerical abilities in newborn humans and newly hatched guppies and chickens — species whose newly-hatched brains are highly developed. However, prior to this study there has been little understanding of numerical abilities in non-human species that are born at a larval or foetal stage, with underdeveloped brains.

Tyrone Lucon-Xiccato and colleagues tested whether recently hatched zebrafish larvae could recognise differences in the quantities of vertical black bars printed onto the white walls of a tank. Larvae were initially raised in tanks with walls covered in a pattern of vertical black bars. After 96 hours, 180 individual larvae were placed in the center of a separate tank, which featured two white walls with different quantities of up to four black bars printed onto them. The researchers observed whether larvae swam towards the larger or smaller quantities of black bars, or remained in the centre of the tank, and timed how long larvae spent in each tank section. In control tests with 120 larvae, the authors repeated the experiment while controlling for differences in the density, surface area, and overall shape of different quantities of bars.

The authors found that 63.1% of larvae preferred the tank walls featuring larger quantities of black bars and spent almost twice as much time near larger quantities of bars than smaller quantities (56.9 seconds vs 32.0 seconds). Among 30 larvae given the choice between walls featuring one and four bars, 66.5% preferred the larger quantity of bars. In tests controlling for bar density, surface area, and overall shape formed by different quantities of bars, 63.2% larvae preferred walls featuring larger numbers of bars. Together, these findings indicate that zebrafish larvae can recognise differing quantities of black bars and that they prefer larger quantities.

The authors suggest that the presence of numerical abilities in both newborn humans and newly hatched zebrafish larvae — two distantly related species — could indicate that numerical abilities are a hardwired, ancient feature of the developing vertebrate brain.

doi: 10.1038/s42003-023-04595-7


メールマガジンリストの「Nature 関連誌今週のハイライト」にチェックをいれていただきますと、毎週各ジャーナルからの最新の「注目のハイライト」をまとめて皆様にお届けいたします。