Evolution and humans: big brain size uses energy (Evolution)

by David Turell , Wednesday, November 08, 2017, 14:23 (2570 days ago) @ dhw

DAVID: This is the one example I've found. Lucy's anatomy is so different many changes are required. The fossils don't provide them.

dhw: So how on earth does that prove that your God changed one lumbar vertebra 23 million years ago in order to prepare the way for Lucy 20 million years later (in order to prepare the way for Homo sapiens)?

Preparation for bipedalism had to start somewhere and at some time. You don't accept goal oriented evolution managed by God.

DAVID: I see no driving force in environmental challenges, but I see a force in God.

dhw: Challenges and opportunities. You cannot see that if food was scarce on land, organisms might be forced to seek it in nearby water, or if trees disappeared, tree-dwelling organisms might be forced to spend more time on the land, and such changes might lead to changes in the anatomy? Meanwhile, do you really believe that God was "driven" to specially preprogramme or dabble eight pre-whales, the weaverbird’s nest, the skull-shrinking shrew because it was the only way to keep life going until he could produce the brain of Homo sapiens?

Of course all living organisms have to seek food, but that is not prove they have to modify to the point of speciation.. All Darwin's finches do is modify beaks back and forth in size. I do believe God drives speciation because of all the planning an design involved. I've not changed my views.

DAVID: Once again you are stretching epigenetic adaptations into an explanation for speciation. It is not, as it only describes adaptation. As for hominins, each stage is a new species, isn't it, requiring the process of speciation?!

dhw: I am proposing a hypothesis to explain speciation. We know there is an autonomous mechanism for minor change, but we don’t know if it is capable of major change. (But it is sometimes difficult to draw a line between adaptation and innovation.) As for speciation, you know as well as I do that it is difficult to define. Since the ability to interbreed is often used as a definition of the broader sense of the word, and we know that different varieties of hominin interbred, it is not unreasonable to say that brain expansion does NOT constitute what you call “full speciation”. But classification is not the real issue here. The question is the potential inventiveness of the autonomous mechanism which enables brains to complexify and shrink of their own accord.

The shrinkage of the brain is at the same level of modification as Darwin's finch beaks, epigenetic, nothing more. You cannot escape brain size changes implying speciation. Body proportions also changed. Just compare us to Neanderthals. There are a whole herd of various hominins with various brain sizes and body shapes, literally a bush of them, many not in our line.

dhw: You are clutching at semantic straws. Being able to do what he wants, and choosing to sacrifice control most of the time (i.e. allow a free-for-all) is a million miles away from being able to do what he wants and controlling every innovation, lifestyle and natural wonder in the history of evolution.

DAVID: But God is in control making your proposed choices. It is God who is making the choice!

dhw: Of course God, if he exists, makes the choice, and in my hypothesis he chooses to allow a free-for-all, which is the opposite of choosing to control everything.

And then you always add He can step in and dabble! You imply He carefully watches a free-for-all. And if He dabbles He guides it. You can't have it both ways.