左利きはなぜ少ない？ 約1割が1万年以上変わらない理由を「ケンカ」と「協力」の進化から読み解く

Q1. What is the passage mainly about?

1. AWhy about ten percent of people are left-handed
2. BHow to write with your left hand
3. CHow caves were made long ago
4. DWhy tools are expensive

左利きが約1割に保たれている理由を説明しているので A。

Q2. What do the old hand prints in caves show?

1. AMost people were left-handed long ago.
2. BNobody was left-handed long ago.
3. CThe number of left-handers has not changed much.
4. DPeople did not use any tools.

this number has not changed much for more than 10,000 years とあるので C。

Q3. In the passage, "rare" means ...

1. Avery strong
2. Bnot common
3. Cvery old
4. Deasy to find

rare は「まれな・めずらしい」。左利きは10人に1人と少ないので B。

Q1. What is the passage mainly about?

1. ALeft-handed people live longer than right-handed people.
2. BHow coaches train left-handed athletes
3. CWhy caves in Europe are popular with tourists
4. DWhy left-handers remain a stable minority of about ten percent

左利きが約1割の少数派のまま保たれている理由を説明しているので D。

Q2. What was the best estimate in the 2020 review?

1. A9.3 percent
2. B10.6 percent
3. C18.1 percent
4. D50 percent

gave a best estimate of 10.6 percent とあるので B。

Q3. According to the fighting hypothesis, what would happen if left-handers became very common?

1. ATheir advantage in fights would become smaller.
2. BThey would win even more fights.
3. CTools would become easier to share.
4. DCave hand prints would change.

有利さの理由は「少数派で相手が慣れていないこと」なので、左利きが増えれば有利さは小さくなると推測できる。A が正解。

Q1. What is the passage mainly about?

1. AHow to become a successful boxer
2. BWhy left-handedness has stayed at about ten percent and what may maintain it
3. CHow cave paintings are dated
4. DWhy left-handedness is determined mainly by one gene

左利きの割合が昔から約1割で、それを保つ仕組み（闘争と協力）を論じているので B。D は本文と逆。

Q2. What did the comparison of cave hand stencils show?

1. AAncient people were mostly left-handed.
2. BModern students made better stencils.
3. CLeft-handers disappeared after the Paleolithic period.
4. DThere was no difference in the proportion of left-handers.

the proportion of left-handers showed no detectable difference とあるので D。

Q3. What limitation of the fighting hypothesis does the author point out?

1. AIt cannot explain any sports data.
2. BIt was first proposed only in 2019.
3. CThe evidence is correlational, and benefits for survival or reproduction have not been shown.
4. DIt ignores the role of shared tools completely.

That evidence is correlational, though. Nobody has shown that such an edge ever helped left-handers survive or have more children. とあるので C。