Jenny McElwain

speaker

162 appearances 1 recordings 1 series first heard Jul 2026 last heard 2 Jul

Jenny McElwain’s voice in public audio — every appearance, attributed to the second.

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Recordings per month over the last 12 months — 1 in all, peaking in Jul 2026 with 1.

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In Our Time · The Evolution of Trees · 2 Jul 2026 podcast

You can see you've hit us.

We're not zoologists.

And I think also even if you don't have a good fossil record of the animals or the insects, we have trace fossils.

So we have the indirect evidence.

So often we will look at the fossil leaves and we can see very diagnostic feeding behavior.

So we see...

mining and margin feeding and hole feeding.

And in some cases, colleagues and paleobotanists have been able to identify the first occurrence of a beetle or the first occurrence of a bee, not based on the body fossil of the animal, but on its diagnostic feeding behavior.

Yeah, preserved on the leaves.

So we know that the tallest living tree recorded is about 116 meters tall.

And I was looking at a good analogy.

I think Big Ben is around 80, 90 meters.

So it's taller than Big Ben.

And there's a group of physicists mainly and plant scientists in Berkeley.

And they actually did a really nice theory paper and they asked,

What is the limit of tree height?

And they determined it's about 140 metres.

And what limits a tree from ever getting taller than that is that wood, those xylem cells, suck water up under tension and negative pressure.

And the water has to get from the roots all the way up to the leaves at 130 metres tall of the tree.

And you break that flow of water.

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