Neanderthal’s Ebb and Flow #poem #anthropology #DNA

The floor of a cave
Holds subtle clues,
Genetic remnants
Preserved in the ooze.

Molecular treasures
Hide in dirt layers,
From blood or from skin,
Or lumps of whatever.

Statistical methods
Link populations
Throughout ancient Europe’s
Inter-glacial locations.

When ice returned
The Tree of Life shook,
Layers of soil,
Are leaves
in humanity’s book.

Classic Neanderthal image from 1920

Thanks to sciencemag.org for their article on a report in Science that dirt from Northern Spain has yielded the first nuclear DNA from an ancient human to be gleaned from sediments:

The sequences reveal the genetic identity and sex of ancient cave dwellers and show that one group of Neanderthals replaced another in the Spanish cave about 100,000 years ago, perhaps after a climate cooling. “They can see a shift in Neanderthal populations at the very same site, which is quite nice.”

This is Impossible, But I Read it Anyway #fossil #dinosaur #DNA

Dinosaur Hypacrosaurus  artist's reconstructionCartilage with DNA’s chemical signature? From a dinosaur? Preposterous.

One study found that half of remaining DNA deteriorates every 521 years. Granted, different levels of preservation exist, but that says finding wooly mammoth DNA is amazing. Dinosaurs? Impossible.

But if there’s any chance at all, it’s fascinating.

Chinese Academy of Sciences paleontologist Alida Bailleul and her colleagues think they’ve got the proof.

Okay – I see “China” and I’m more skeptical than usual. Some questionable reports come out of China. But so do some remarkable fossils.

What about bacterial contamination, whether recent or ancient? What about analytical errors handling what-must-be tiny samples? Should we even talk about this before replication studies are published?

Keep an eye open. Every controversial field of study had to start someplace.

Most Basic to Life #biology #science #poem #poetry #whatislife

Code?

Are you alive?
How do you know?
What do you look at
To see if it’s so?

Is it because
You oxidize food?
Consume and create
Organic
Molecules?

Or the homeostasis
That you maintain?
Do you need cells
To be in the game?

What if the planets
Hold a surprise?
Organized data
May say you’re alive.

Kate Rauner

Thanks to sciworthy.com for raising the question, even if there’s no consensus answer. For you and me, “I think therefore I am” may work as well as any other answer.

You’re a Mutant and it Gets Worse Every Day – Here’s How #biology #gene #radioactive #DNA #Asimov

DNA structure

DNA, just peppered with carbon atoms

Does the thought of mutations in your DNA (and other bits of your body’s cells) scare you? Do you worry about toxins, or GMOs, or species-hopping viruses? Cancer, or growing a second head? Here’s something that may terrify you. Or, since it happens every day and you’re not dead yet, maybe comfort you.

Here’s how you mutate. Your body contains a lot of carbon. This is such a basic fact that to say a chemical is organic means it contains carbon atoms in its molecules. Your DNA, the genetic blueprint that pilots your cells through life, contains carbon atoms.

Not likely!

Carbon, like many elements, exists in different forms called isotopes. Mostly we have carbon-12, but a fraction of all carbon is carbon-14, which is radioactive. When it decays (that is, releases a sub-atomic particle or energy from its nucleus), it transmogrifies into a different element, nitrogen.

Isaac Asimov once estimated that this transmogrification happens roughly six times a second somewhere in the DNA in your body, every second of every day, throughout your life. I’m way too lazy to check his figures, but whatever the rate, it happens. Every one of these events mutates the DNA where it occurred. A lot of the mutations will be in body cells, and some will be in sperm or eggs (reproductive cells.) A mutation might kill the cell, cause cancer, get passed on to offspring, or do nothing discernable.

So, you are a mutant. So am I. And we’re still alive. Do you feel better? Or worse?

BTW: Carbon-14 is created in Earth’s atmosphere every day by a natural process. Cosmic radiation strikes our planet from every direction, and it includes sub-atomic particles known as neutrons. Occasionally a neutron strikes a nitrogen atom. Our atmosphere is roughly 75% nitrogen, so this is no surprise.

The neutron reshuffles nitrogen’s nucleus and transforms it to carbon-14, which is radioactive and so decays back to nitrogen. It takes 5,700 years for half of a given amount of C-14 to decay, but it happens at a steady rate. The entire process happens at a steady rate and the C-14 way up high mixes into the air down low that we breathe, so the amount of C-14 in the body of any living organism stays constant until it stops breathing (or otherwise respiring). Then radioactive decay depletes the body of C-14. This is the basis of carbon-14 dating, which you may have heard of.

BTW2: Asimov’s book is old – published in 1988 – but still worth reading. He covers a lot of history and basic science. New discoveries seldom change what we know about the basics, like radioactive decay.