(no subject)

I'm sure folks across Australia are choking on their Oorn Flakes* in astonishment at the AG's admission that "arrests might not follow the hurried passage of an amendment to counter-terrorism laws".
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* To make Oorn Flakes, take a box of Corn Flakes and a thick black Texta, and complete the circle of the "C" in "Corn". Long personal tradition of mine, or it was when I could still eat them (GI = 77).

(no subject)

Why do fish have noses?

Irregular Webcomic

OK, first read this one, starring the artist himself.

Now you're ready to read this one.

PSA

When Love walks in the room
Everybody stand up.
- The Pretenders

Evidence for Macroevolution and Common Descent - 2

The next bit of 29+ Evidences for Macroevolution is a daunting introduction to phylogenetics. Luckily, the author says we can have an early mark before the really technical stuff! Anyway, let's see how I go with my crummy summary. (Remember, the essay's author doesn't know I'm doing this. Your comments are welcome!)

If life descends from a common ancestor, then it'll be possible to draw a family tree of every living thing on Earth. Such a family tree is called a phylogeny. There will only be one correct family tree - the true history of evolution. The branches of the tree show how each group of organisms (living things) descended from another group, and the relationship between related organisms, just like an ordinary family tree showing parents, grandparents, cousins, etc.

29+ Evidences gives a phylogeny for all life - you read it from the bottom to the top.

These phylogenies are created by looking at the characteristics groups share with each other - you can see how the tree branches when a new characteristic appears, such as chloroplasts or feathers. The "leaves" on that branch all share those characteristics - humans and cows both have placentas, humans and marsupials both have hair, humans and starfish are both deuterostomes (their embryos develop the same way), humans and jellyfish both have a nervous system. The tree branches and branches again - that's called a nested hierarchy.

A phylogeny can be drawn simply, like a train map, which shows how stations connect but doesn't try to accurately show the distance between them; or like a road map, which does indicate "distances" (for example, how similar a particular gene is). The length of the branches is used to show "distance".

The mathematical methods used to create these phylogenies have been tested against known phylogenies (for example, with strains of mice and of viruses, where their pedigrees were already known); the methods were found to be highly accurate.

A short lay explanation of phylogenies can be found at What Is Cladistics?.

In the next installment - the evidence that all life forms are descended from a common ancestor.