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Molecules in million‑year‑old fossils show a warmer, wetter past — Level B1 — brown and white animal paw print textile

Molecules in million‑year‑old fossils show a warmer, wetter pastCEFR B1

26 Dec 2025

Adapted from Rachel Harrison-NYU, Futurity CC BY 4.0

Photo by Wolfgang Hasselmann, Unsplash

Level B1 – Intermediate
4 min
191 words

A new study published in Nature reports the extraction and analysis of metabolism-related molecules from fossil bones dated between 1.3 and 3 million years. The research team tested the idea that molecules carried in life could become trapped in tiny spaces in bone and remain over time.

Scientists first analysed present-day mouse bones and identified nearly 2,200 metabolites, and they also detected proteins such as collagen in some samples. They then examined fossil fragments from sites in Tanzania, Malawi and South Africa, from species with living counterparts: several rodents, an antelope, a pig and an elephant.

The molecular results revealed biological processes such as amino-acid, carbohydrate and vitamin metabolism. Some molecules pointed to genes linked with estrogen, suggesting certain animals were female. One 1.8-million-year-old ground squirrel from Olduvai Gorge showed a metabolite of the parasite Trypanosoma brucei and signs of an anti-inflammatory response, consistent with infection.

Plant metabolites, including types related to aloe and asparagus, helped reconstruct temperature, rainfall, soil and tree cover. These reconstructions agree with earlier descriptions of Olduvai Gorge layers, and across the sites conditions were wetter and warmer than today.

Difficult words

  • metaboliteSmall molecule produced by living organisms
    metabolites
  • metabolismChemical processes that keep living things working
    metabolism-related
  • collagenStructural protein in bones, skin and tissue
  • parasiteOrganism that lives on and harms another
  • reconstructTo build a past situation from evidence
  • anti-inflammatoryReducing swelling and pain in tissues

Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.

Discussion questions

  • Would you be surprised that molecules can survive for millions of years? Why or why not?
  • How can finding signs of infection in a fossil animal help scientists understand the past?
  • Do you think studying plant metabolites is a useful way to learn about ancient climate? Explain your opinion.

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