Tag: DNA

Human origins

Theorists can move forward again – and the picture seems a little more complicated than we thought.

Where did we come from, and how? We’ve long thought in terms of an evolutionary ‘tree’, but our origins in Africa are more like a braided channel. This idea provides a better fit to the data.

Based on fossil evidence alone, studies of human evolution have long agreed that modern humans evolved in east Africa and radiated out from there. But with the development of cheap, fast and reliable DNA evidence from modern populations, and DNA from fossil teeth and bone samples, it’s becoming clear that theorists can move forward again – and the picture seems a little more complicated than we thought.

Human dispersion, events described in the article all took place in Africa – Image from Wikimedia

On 17th May, Ragsdale and others published a research paper in Nature; ‘A weakly structured stem for human origins in Africa’; their evidence suggests evolutionary connections in populations that were separated for a while before recombining. So instead of an evolutionary tree (which most people were expecting) it seems that our human past is more like a set of braided channels.

Previous views on human evolution proposed a tree structure (branching but not recombining). However, the new ‘weakly structured stem’ model fits the data better than a tree model. It also explains the diversity of genetic forms in modern human populations, and shows that there is no single place in Africa where humans ‘originated’. After this process within Africa, humans spread out as show in the map.

See also:

Evolution and behaviour

A computer program that simulates coding and inheritance on the one hand, and neural function on the other, permits the emulation of simple animal-like organisms

Today I want to share two striking YouTube videos that I found recently. Maybe you’d like to watch them yourself.

Part of a DNA molecule (from Wikipedia)

Introduction – The animation shows the molecular structure of DNA, rotating so you can visualise it more easily. Watson and Crick famously published this structure in April 1953.

DNA contains the genetic information that specifies the nature of plants, animals and other life forms. Each species has it’s own form of this DNA ‘instruction book’. Amongst other things, a species’ DNA controls the basic structure of the brain just as it does for other body parts. But here’s an interesting fact: The coding and behaviour of DNA can be simulated by strings of characters stored in a computer.

Brains involve cells called neurons with connections between them, and neural networks running on a computer can behave in a similar way to a very simple brain. Building a computer program that simulates coding and inheritance on the one hand, and neural function on the other, permits the emulation of simple animal-like organisms, and there are applications out there that do just this.

First example – One such program is Minute Labs’ Evolution Simulator (check out their YouTube to see it in action).

Second example – Another program, and I want to focus mainly on this one, is from David Randall Miller. He wrote a particularly fascinating simulator, see his YouTube demo and explanation below for some quite deep insights. It’s a long video, but breaks into logical chunks for easier viewing; I suggest viewing the first section and continuing if it seems interesting.

It’s a really helpful approach for anyone wanting to better understand evolution. It assumes only fundamental levels of the topics, but will enhance your appreciation of maths and computing while also demonstrating the basics of genetics, inheritance, simple neural networks, and animal behaviour. That’s quite a lot of benefit from just one video!

Some questions to ask yourself…

  • What new understandings did you gain?
  • Did you disagree with anything?
    • If so, why?
  • What conclusions did you draw about the nature of living things?
  • Was anything surprising to you?
  • What questions do the videos cause you to ask?