Home  >  CrowdScience  >  Were humans ever semi-aquatic?
CrowdScience
Were humans ever semi-aquatic?
CrowdScience
Jan 19, 2024

What evidence is there for a semi-aquatic period in human evolutionary history? That’s the question that’s been bothering listener Dave in Thailand. He thinks our lack of hair and love of water might indicate that, at some point, we were more water-based than we are now. But what does science have to say on the matter?

The theory that our ape ancestors returned to the water for a phase in our evolutionary history is a controversial idea that most scientists disagree with.

Anand Jagatia chats to Dr Melissa Ilardo, assistant professor at the University of Utah, about our dive reflex - a physiological response we display when submerged underwater, which helps direct oxygen towards vital organs. But this is not a response that is unique to humans - it is found in all mammals. Experts say it developed long before all apes split off in the evolutionary tree.

To find out more about the theory itself Anand hears from John Langdon, emeritus professor at the University of Indianapolis. He explains why the aquatic ape theory is not generally accepted by anthropologists, what the fossil record can tell us about our evolutionary path and why evolution is much more complex than the aquatic ape hypothesis suggests.

While there may be little evidence of a semi-aquatic period in our evolutionary past, there are some communities around the world that have adapted to utilising their watery environments in more recent evolutionary history.

Anand speaks to Dr Nicole Smith-Guzman at the Smithsonian Tropical Research Institute who has found evidence that ancient populations in Panama were habitually diving in the sea for shells and seafood. She explains how she can piece together evidence from different sources to detect the activity of ancient populations. And Dr Melissa Ilardo explains how evolutionary pressure can cause physical changes in isolated communities, as our bodies ultimately adapt to help us thrive in more watery environments.

Producer: Hannah Fisher Presenter: Anand Jagatia Editor: Richard Collings Production co-ordinator: Jonathan Harris Sound engineer: Jackie Margerum

(Photo: Woman swimming underwater. Credit: Petrelos/Getty Images)

More Episodes
May 8, 2026
How come sea levels are rising faster in some places than others?

As our oceans warm due to climate change, sea levels are rising. It ought to be straightforward – as water gets warmer, it increases in volume.

All the world’s oceans are connected, so how come sea levels are rising at different rates around the world, and even falling in some places? CrowdScience listener Alison in Australia wants to know the science behind the mystery.

 Presenter Anand Jagatia travels to the Philippines to investigate. The country is being particularly affected by the issue, with its more than 7,500 islands experiencing sea level rises that are double the global average.

On Palawan Island, in the east of the country, he speaks to people whose homes and livelihoods are being put at risk by rising waters.

He also visits the Philippine Coast Guard in Manila and speaks to Commander James Barandino, from their Marine Environmental Protection division, to hear how their work is being affected by sea level rises and the flooding it causes.

Dr Charina Lyn Repollo from the University of the Philippines Marine Science Institute shows Anand how they monitor sea levels at dozens of locations. Their data shows huge variations in sea level across the country. How can that be the case?

Anand also speaks to Jonathan Bamber, Professor of Earth Observation and Glaciology at the University of Bristol in the UK, to unpick the science behind how sea levels can rise at different rates in different places.

And how do we protect people from rising waters? Dr Rodel Diaz Lasco from the Oscar M. Lopez Center for Climate Change Adaptation and Disaster Risk Management in Manila, explains how global collaboration might hold the key.

Presenter: Anand Jagatia

Producer: Dan Welsh

Editor: Ben Motley

(Photo: Globe floating on water - stock photo- Credit: Jan Hakan Dahlstrom via Getty Images)


31min 24sec


Apr 24, 2026
Do animals hold funerals?

CrowdScience listeners Dougie and Molly have been wondering what happens to animals when they die, and whether there are animals that hold rituals to mark the passing of one of their kin.

Presenter Caroline Steel is on the case, trying to work out what happens to the bodies of animals when they die. Dougie and Molly say they rarely see animal carcasses where they live - so where do they all go?

Dr Sarah Perkins of Cardiff University in the UK runs a research project called Roadlab, which logs how quickly the bodies of animals killed by traffic disappear, and she thinks she might have a clue. Caroline joins her on a hunt through the undergrowth for animals, and answers.

And when animals lose a member of their flock, herd or school, do they indulge in rituals that look anything like a funeral? Caroline meets Dr Kaeli Swift, an ecologist at the University of Washington in the US, who has some surprising evidence from her research into bereaved crows.

Meanhile, in Botswana, Mathale ‘Metal’ Mosheti is a safari guide in Chobe National Park. The African Savannah Elephants there demonstrate some remarkable behaviour when another elephant dies. But do animals really grieve for their loved ones? Dr Barbara J. King, Emerita Professor of Anthropology at William & Mary University in the US, has some ideas. But is it enough to answer Dougie and Molly’s question?

Presenter: Caroline Steel

Producer: Tom Bonnett

Editor: Ben Motley

(Photo: Little red sick bird canary inside a wheelbarrow pushed by a lizard. Credit: Fernando Trabanco/Getty Images)


26min 28sec

Apr 17, 2026
Why does salt taste so good?

Salt can be found in almost every kitchen in the world. But how did this seemingly simple ingredient become the world's favourite flavour enhancer?

This week, Crowdscience sets out to uncover why these tiny crystals have such a powerful effect on us. We explore the magic behind this tiny mineral that has shaped our tongues, our culture, and our cravings.

Our investigation begins with CrowdScience listener George, who heard from a friend that if he added a few grains of salt to his morning coffee, he could make it taste less bitter. Following some light investigation at his local coffee chain, he began wondering why salt make things taste more delicious.

To try and find an answer, presenter Anand Jagatia heads to a salt mine in Austria with Daniel Bradner, an archaeologist from the Natural History Museum of Vienna. The mine is 200 kilometres from the sea, so where does all the salt come from?

In London, UK, we meet Adriana Cavita, a chef who helps us explore how salt transforms what we eat:  sharpening aromas, softening harsh flavours, and boosting sweetness.

We explore the receptors inside our mouth with taste expert Courtney Wilson from the University of Colorado School of Medicine in the US, to find out how we detect whether there’s too much or too little salt in our food.   

And we meet Joel Geerling, Associate Professor of Neurology at the University of Iowa, US, who’s been looking inside the brain to try and work out why we crave salt. He’s discovered an incredible system that’s highly engineered to give us an appetite for salt. Could it be the answer to George’s question?

Presenter: Anand Jagatia

Producer: Robbie Wojciechowski

Editor: Ben Motley

(Photo: Measuring Teaspoon of Sea Salt with Vibrant Colors - stock photo JannHuizenga via Getty Images)


26min 28sec

Were humans ever semi-aquatic?

--:--
--:--