what does this sentence mean

[spinoza99]

This comes from a book that tries to prove Darwinism, The Making of the Fittest by Sean Carroll:

most animals are endowed with similar tool kits of body-building and organ-building genes (our phylum, the vertebrates, does have a larger number of these tool-kit genes because of some large-scale genome duplications). This tells us that the tool kit itself is ancient and must have been in place in a common ancestor before most types of modern animals bodies and body parts evolved.

Is he saying:

1. body-building genes were built before they were used or
2. body-building genes were used as soon as they were built and they are still being used today

[Thinking Aloud]

Without having read the book, and without the full context, I would imagine it means neither of the options you've provided.

[Gawdzilla Sama]

That's one sentence and sentence fragment.

[Gawdzilla Sama]

This comes from a book that tries to prove Darwinism, The Making of the Fittest by Sean Carroll:

most animals are endowed with similar tool kits of body-building and organ-building genes (our phylum, the vertebrates, does have a larger number of these tool-kit genes because of some large-scale genome duplications). This tells us that the tool kit itself is ancient and must have been in place in a common ancestor before most types of modern animals bodies and body parts evolved.

Is he saying:

1. body-building genes were built before they were used or
2. body-building genes were used as soon as they were built and they are still being used today

I'm betting neither is correct. It means we're of common ancestry.

[spinoza99]

ok, I contacted the author and he responded in about 6 hours and said that it's the second interpretation that is correct

[Xamonas Chegwé]

ok, I contacted the author and he responded in about 6 hours and said that it's the second interpretation that is correct

That makes sense. One of the first sets of genes necessary for multicellular organisms to evolve from simpler unicellular ones would have to be those dictating embryonic development.

[GenesForLife]

This comes from a book that tries to prove Darwinism, The Making of the Fittest by Sean Carroll:

most animals are endowed with similar tool kits of body-building and organ-building genes (our phylum, the vertebrates, does have a larger number of these tool-kit genes because of some large-scale genome duplications). This tells us that the tool kit itself is ancient and must have been in place in a common ancestor before most types of modern animals bodies and body parts evolved.

Is he saying:

1. body-building genes were built before they were used or
2. body-building genes were used as soon as they were built and they are still being used today

Genes that were present in a common ancestor (of an ancient origin) and duplicated copies derived from those genes work/are used by organisms during the development of body parts.
And it isn't a book that tries to prove Darwinism, for two reasons, really.

[1] 'Proof' is only used in axiomatic deductive systems, Evolution is the result of a hypothetico deductive system.
[2] The fact that genes and copies of genes can be co-opted is an evidentially supported fact.
[3] The book is just an account for laymen about some of the features of evolutionary processes.

look at this, for instance.

Gene A, Gene B and Gene C are all involved in development.

Common ancestor with Gene A,B,C -----------------------> Descendents with A, B, C, with those genes used for development.

Remember this, genes that performed one function or mutant copies thereof can start to perform different functions, an example is here, wherein phylogenetic evidence indicates that steroid receptors evolved from duplicated copies of an ancestral estrogen sensitive receptor.

The evolution of novelty in tightly integrated biological systems, such as hormones and their receptors, seems to challenge the theory of natural selection: it has not been clear how a new function for any one part (such as a ligand) can be selected for unless the other members of the system (e.g., a receptor) are already present. Here I show—based on identification and phylogenetic analysis of steroid receptors in basal vertebrates and reconstruction of the sequences and functional attributes of ancestral proteins—that the first steroid receptor was an estrogen receptor, followed by a progesterone receptor. Genome mapping and phylogenetic analyses indicate that the full complement of mammalian steroid receptors evolved from these ancient receptors by two large-scale genome expansions, one before the advent of jawed vertebrates and one after. Specific regulation of physiological processes by androgens and corticoids are relatively recent innovations that emerged after these duplications. These findings support a model of ligand exploitation in which the terminal ligand in a biosynthetic pathway is the first for which a receptor evolves; selection for this hormone also selects for the synthesis of intermediates despite the absence of receptors, and duplicated receptors then evolve affinity for these substances. In this way, novel hormone-receptor pairs are created, and an integrated system of increasing complexity elaborated. This model suggests that ligands for some “orphan” receptors may be found among intermediates in the synthesis of ligands for phylogenetically related receptors.

http://www.pnas.org/content/98/10/5671.abstract

I am also going to try and get across a concept here, which can be a bit difficult to grasp, so do concentrate.

[1]Genes and gene products can act in networks.
[2]Mutations in promoters can change how much a gene is expressed, or when.
[3]Mutations in transcription factor can achieve the same effect.
[4]Changes in the networks themselves can have different effects, in other words, the number of genes does not impose any sort of upper bound on phenotypic diversity, you can add a multitude of parameters. This is one reason why cancer is so screwed up, since rapid mutation allows them to develop a large number of phenotypes through different means, for example, they can experience silencing wrt a gene called p53 or produce mutated copies that are functionally deficient ,which stops growth in abnormal cells or they can experience mutations in a competitive inhibitor (roughly) called Mdm2 which can prevent p53 from acting even if it is normal.


So even when you have the same genes with altered regulation acting in different permutations and combinations, you still get different phenotypes, regulatory mutations are usually cis-regulatory in nature.

The summum bonum of all that is this, the plastic nature of genes means there is more than one way to skin a phenotypic cat.

[Tero]

It's still a bit mysterious how an embryo grows into an organism. It's in that recent Dawkins book about the BIG show. Anyway, several genes may act together or in sequence so not all of the instructions are new to the organism, just some parts evolved for the last version.

[GenesForLife]

It's still a bit mysterious how an embryo grows into an organism. It's in that recent Dawkins book about the BIG show. Anyway, several genes may act together or in sequence so not all of the instructions are new to the organism, just some parts evolved for the last version.

Not exactly for all organisms, Tero, for organisms such as the Sea Urchin, which has, among other things, genes that function in the development of our eyes (they're on the same evolutionary branch as we are) and some of the genes involved in immune system development and functioning, detailed pathways are available.

A wonderful resource on this would be Eric Davidson's "The Regulatory Genome"

[Tero]

Right, thanks.

[GenesForLife]

Right, thanks.

If you want a copy I can sort one out.

[Tero]

No, thanks, I am on vacation and burning discs to take to a friend all morning. So he can have my entire British progressive rock collection.

Plus reading hurts, too much work.