Evolution & Genetics questions

21 fact-checked questions — tap any to predict the answer, then read why.

• Which of the following best describes a common change in RNA transcript length with age?
• Why do different organs in mammals show different gene activity patterns related to longevity?
• What can researchers learn about people of the same age from separate RNA-based aging clocks that estimate age from inflammation-related and metabolism-related gene activity?
• If you sort the many gene-activity changes that come with age into groups that rise and fall together, what does that grouping reveal?
• Why might aging mouse, monkey, and human cells show similar changes in the RNA they produce across different tissues?
• Why does a platypus still count as a mammal when it lays eggs and has no nipples?
• Platypus bills and some dolphin whisker pits both sense weak electric fields. What evolutionary pattern does this illustrate?
• Why do platypuses have around 40,000 electroreceptors while short-beaked echidnas have only around 400?
• Why can a plankton species die out after a food shortage leaves only a few survivors, even once food returns?
• In asteroid darkness, why did some algae survive by becoming less plant-like?
• Why did freshwater animals survive the asteroid impact winter better than land animals?
• Why might the salt gland of a spinosaur, a fish-eating dinosaur with a long crocodile-like snout, have sat just above its eye?
• Why do spinosaur skull grooves hint at salt glands?
• Why did humans rely on clothing rather than re-evolving a thick coat?
• Why didn’t humans’ loss of body hair wipe them out by making cold easier to feel?
• If losing most body hair helped humans cool down, why did hair remain on the head, eyebrows and eyelashes?
• Why do humans have much less body hair than most mammals?
• Why do we have wisdom teeth?
• Why do giraffes have long necks?
• Why can't penguins fly?
• Why do many fleshy fruits become sweeter as they ripen?