Researchers studied the family Scombridae, which includes tunas and mackerels. They combined genetic data with fossil specimens to make a time‑calibrated evolutionary tree for the group.
The analysis showed that Scombridae began near the time of the asteroid strike 66 million years ago. However, large body size and warm‑bloodedness (endothermy) appeared later and at different times in separate lineages. The study found endothermy evolved three times, and at least two of those events occurred 10 to 15 million years after the asteroid strike.
The authors say better knowledge of tuna evolution can support conservation, noting that Atlantic bluefin tuna populations have declined because of overfishing.
Difficult words
- genetic — about genes and DNA in organisms
- fossil — a preserved part of an ancient animal or plant
- endothermy — ability of an animal to keep itself warm
- lineage — a family line of animals or plants over timelineages
- evolve — to change slowly over many generationsevolved
- conservation — protection of nature, animals and their habitats
- overfishing — catching too many fish, reducing their numbers
Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.
Discussion questions
- Why might knowing the evolution of tuna help conservation efforts?
- What can people do to reduce overfishing of tuna?
- Is it surprising that warm‑bloodedness evolved several times? Why or why not?
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