Dr. Lawrence David
speaker
102 appearances
1 recordings
1 series
first heard Aug 2026
last heard 5 Aug
Dr. Lawrence David’s voice in public audio — every appearance, attributed to the second.
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recordings per month · last 12 monthsRecordings per month over the last 12 months — 1 in all, peaking in Aug 2026 with 1.
Appearances
Science Friday · What do people eat? Plant and animal DNA in sewage provide clues · 5 Aug 2026
podcast
The thing is that we eat a lot of it.
So...
We estimate that people are eating maybe up to a gram of DNA a day, so billions of copies of the genes that we sequence.
And so even if 99% are degraded, there are still millions of copies per person that can be ultimately amplified out and sequenced.
And also, when we go back, anthropologists have done this and archaeologists, you can get DNA from poop samples that go back hundreds of years, sometimes further than that.
So DNA can really stick around.
Depending on where you're sampling, someone might go, say, to a wastewater treatment plant.
Right as the sewage is entering, someone will scoop out some of that wastewater.
liters, so a decent amount.
You can do it two different ways.
You can scoop out liters or suck out liters of fluid.
You can do it all at once, or you can do it over the course of, say, 24 hours.
And the other way you do it is that you kind of lower down something very absorbent, and that sort of sucks up material and DNA.
You can do both.
You should probably ask for permission if you're going to do either of those things, which we generally do.
But yeah, I think that we've been really delighted with how open and helpful a lot of people who work with wastewater have been in letting us take a peek.
It is.
When things come out, it's always fascinating to us if we see something we haven't seen before.
And honestly, just if the experiment works, I really didn't think it would work in the beginning or I didn't know what to expect.
And so when we saw it, it was amazing.
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