: Actually it is. DNA alone provides overwhelming evidence in favour of it.

My favorite example is endogenous viral elements (EVEs).

Creationists often explain the nested hierarchies and homologies as being due to common design rather than common ancestry. Same designer: same designs. The designer could choose to base new designs on top of old. He could chose to make tweaks instead of starting afresh like wot a straightforward interpretation of the bible would suggest (if said designer was the biblical god).

But EVEs are the marks of ancient viral infections. Each one got into an animal's genome because an ancestor caught an infection and part or all of a viral genome was incorperated into the genome of a germ line cell. Once a viral fragment gets into the germ line then it will be found in every cell of that organism's descendants and these fragments tend to hang around for a very long time (tens or hundreds of millions of years). They are copied along with the rest of the DNA in each cell.

I can't think of a really good analogy right now so I'll use a not very good one ;-) Think of scratches and coffee stains on tables. In addition: imagine if tables were made by 'photocopying' existing tables. As if tables, who loved each other very much, got married and had babies.

A person could argue that tables inherit their legs from their parent tables and that the features of tables are inherited from their ancestors. But someone else could argue that those features were initially put there by a designer.

It's harder (silly? impossible?) to argue that the scratches and coffee stains were put there by a designer. (Should we ignore the possibility of an artistic table vandal? Should we attribute all table damage to the acts of such a long lived vandal?)

We can deduce how the scratches and stains got there. We could identify cat scratches on the legs, scratches due to bread knives, burns due to cigarettes, etc. We could tell when some scratches overly others. These signs of damage are direct evidence of historical events - things that happened to a distant ancestor of the table's being studied.

It is the same with EVEs. They directly testify to past events - the shared histories of disparate genomes. If bats, humans, and cats share an EVE in the same location then they got that from a common ancestor who caught an infection that got into its germ line cells.

We can do statistical analyses of EVEs right across all clades of animal life and we find that the distributions match those derived from DNA sequences that code for features that are selected for - things that encode proteins or gene switches - things that could be said to come from either design or evolution. And these correspond well to trees made from skeletal features and other physical features of animals.

: Oh. Micro vs. macro evolution? The distinction is basically bullshit.

Yeh, lions and tigers and leopards, and sabre tooths, and house cats are all, obviously still cats and yet are also separate species. But we can cross the living ones with varying degrees of success so what does that say about species? Are species just human conventions? Are there really only cats? Do we say that cat is a real grouping and that the species are just arbitrary human conventions?

Where do we draw the line?

Are all cats related and all dogs related and all monkeys and apes related but humans, cats, dogs, and primates are all separate?

When we look at the evidence we don't find those clear demarcations. Cats and dogs are related. They are also related to hyenas. Hyenas are more closely related to cats than they are to dogs. We can see that all the carnivora are related to varying degrees.

All the things mentioned above are placental mammals, they all share features (and evidence of ancestral infections) with each other and with marsupial mammals.

Mammals share a grouping with reptiles: they are all amniotes (have a membrane that encloses the embryo in a fluid capsule that originally protected it from drying out on land when in the egg).

All amniotes are tretrapods (4 legged land animals) they share this feature with the amphibians (amphibians do NOT have amniotic eggs and so are not amniotes).

All tetrapods are vertebrates and share having a backbone, segmented body plans, neural crest cells and other developmental and biochemical features. Fish are also vertebrates.

And so on and so forth until we join up with the bacteria and archea. All life is related.

: Evolution happens over generations. Successive generations got faster at
: woodpecking because it was an advantage to do so in their environment. One
: bird didn't suddenly decide to peck that fast.

Their ancestors could start out pecking at dead, fallen, decayed wood. It's soft and has plenty of insect life in it. But, obviously, being able to tackle harder wood and having a longer tongue would give individuals access to more food and those things could be selected for.

There is no in principle reason that woodpeckers could not have evolved.

: Monkeys did not evolve into Humans. Principally because we're APES (no
: tails) and not monkeys. We share a (relatively) recent ancestor with apes
: compared to the other species. We didn't descend from gorillas; we're
: close cousins.

I think that the two monkey clades obviously share a common ancestor so are a single clade. There is no reason to exclude the apes from the monkeys. So I'd say that apes are monkeys: humans are apes and so humans are monkeys. In my opinion the distinction between apes and monkeys is an artificial one.