Human lead climate change didn’t start yesterday

… or even 200 years ago but more likely 5000 years ago !


Human power and responsability

There is no natural environment. Or at least so little left. Most of what you think about is not untouched nature. Apples have tremendously changed, selected by the human hand. Same for wheat, cows, … So little we eat is untouched nature. Same for the landscape. A park isn’t. Most forests aren’t, including much of the Amazon Forest. Whether you like it or not we shaped the world in so many ways, but so little compared to what plant did: those folks, together with a bunch of microorganisms created dirt and made the atmosphere oxygen rich!
Life thrives on those telluric transformations. But we also invented concrete and dragging nets. And life is having a setback. Sure we are part of life and currently a decisive change force. It is on our shoulders to take the fabulous adventure of life to new heights or to empty it. Bit by bit.

Are we more bacteria than human ?

Didn’t you have this discussion with your scientific minded friends: so many bacteria in your intestine, on your skin etc. that actually you may be more bacteria than human? I sure had this discussion with two Ivy League university professors who were 100% sure there was more bacteria than human DNA in the typical 70kg man.

So what are the orders of magnitude?

A recently published PNAS article sets the records straight:

  1. There are slightly (<3%) more bacteria than human cells in a human body
  2. Their total mass is 350 times less than that of human cells

That implies that total DNA content is about 1000 times less than total human DNA as the number of cells is about the same and the human genome at ~3 billion base pair is 1000 times the typical bacterial genome size.

Of course that’s without counting mitochondria which might be considered as endosymbiotic bacteria.

So sure, bacteria in a human body are important, but not completely overwhelming our “own” genetic information 🙂