I've discussed this before:
but I'd like to make an additional observation. Take a comparison: camouflage in general is functional. It conceals prey from predators. Conversely, it conceals ambush predators or predatory stalkers from prey.
However, many animals don't simply have camouflage, but symmetrical camouflage. That, however, isn't functional. Indeed, it's somewhat counterproductive because it makes the animal easier to detect. The symmetry doesn't blend into the background. That's why military fatigues use disruptive coloration to break up the outlines of a soldier.
A Darwinist may say camouflage mirrors bilateral symmetry. But while that may be true, it doesn't confer a survival advantage. It has no evolutionary utility.
Moreover, many animals have disruptive coloration or countershading, so the evolutionary explanation isn't consistent.
BTW, this is a problem with evolutionary explanations: if a feature is functional, the Darwinist says that's adaptive, but if the feature is useless or counterproductive, they say that because evolution is blind. So the theory is too flexible. Something and its contrary are both evidence for evolution!
BTW, this is a problem with evolutionary explanations: if a feature is functional, the Darwinist says that's adaptive, but if the feature is useless or counterproductive, they say that because evolution is blind. So the theory is too flexible. Something and its contrary are both evidence for evolution!
From a creationist standpoint, male nipples may have the same explanation as symmetrical camouflage: it's decorative. In creationism, not everything has to be functional. Some things may be aesthetic.
I still really don't understand how male/female reproduction was supposed to have evolved under naturalist conditions. Male and female are supposed to have - independently of each other - evolved interlocking parts, perfectly adapted to deliver the sperm to the egg and fertilize it. But how is the male DNA aware of the female DNA and what's required to start the process of reproduction? And of course the worst part is that even minuscule mutations take several generations, so how did anything more complex than an amoeba reproduce in the meantime?
ReplyDeleteSteve,
ReplyDeleteWouldn't the explanation for male nipples just be that the genes responsible for nipples are common to both males and females but, in the case of females, those genes are up-regulated and/or work in concert with other up-regulated genes to produce a more developed breast?
Vaughn,
"Male and female are supposed to have - independently of each other"
Is that right?
Males and females of a species are members of a single species. It is not as though males are one species, and females another species, who just happen to be compatible in terms of reproduction.
I think the Darwinist would say that at the point sexual reproduction began to develop, the relevant organism had both the capacity for asexual reproduction and a proto-capacity for sexual reproduction. I think there are existing species where both forms of reproduction can occur. The asexual reproduction would allow continuation of the species while the proto sexual reproduction capacities were being refined. So initially, the probability of a successful sexual reproduction occurring might have been very low, but where it occurred it was beneficial to the species. And over time this capacity (in the standard ways suggested) was improved.
I don't think early sexual reproduction would even have needed a 'male delivery organ' to be combined with a 'female receptacle organ'. For example, the exchange by viruses and bacteria of genetic information does not occur at this level.
Hi AMC
Delete"Wouldn't the explanation for male nipples just be that the genes responsible for nipples are common to both males and females but, in the case of females, those genes are up-regulated and/or work in concert with other up-regulated genes to produce a more developed breast?"
1. At the risk of oversimplifying, it seems to me Steve's response attempts to address why, whereas your response attempts to address how. I mean it sounds like you're attempting to explain the mechanism in the development of male nipples, but the deeper question is why is it set up this way in the first place? Not so much how do males have nipples, but why do males have nipples?
2. As far as the mechanism goes:
a. It's true the genetic code is in play. To be fair, I think that's just about true for practically every embryological development.
b. At the same time, there's a significant place for maternal hormones. Such as maternal hormones that pass through the placental membrane and enter into the fetal circulation. These hormones significantly influence the development of mammary glands including crests or ridges or milk lines. Here is a good overview.
"Is that right?"
It seems to me what Vaughn has said and what you have said aren't necessarily inconsistent with one another. That said:
"Males and females of a species are members of a single species. It is not as though males are one species, and females another species, who just happen to be compatible in terms of reproduction."
I'm not sure that's what Vaughn is saying. I don't think he's referring to male and female at a species level, but something more fundamental.
"the relevant organism had both the capacity for asexual reproduction and a proto-capacity for sexual reproduction"
Of course, that's a highly debatable issue. What is the nature of this "proto-capacity" and so on.
Hawk,
ReplyDelete"Not so much how do males have nipples, but why do males have nipples?"
What is the distinction you are drawing between "how" and "why"? By "why", are you referring to "reasons" (in the sense of the outcome of mental deliberation or choice)?
As a Christian (indeed calvinist), I agree that God has foreordained everything and that whatsoever comes to pass happens by virtue of God's reasons. However, if you are discussing the matter with a naturalist, then the naturalist will just reject posing a question in a way that assumes reasons are necessary.
Apart from the X or Y chromosome, males and females possess the same DNA instructions for their body plans. It's hardly surprising, on naturalism, that males would have nipples because (although such nipples may not be advantageously functional) nipples are coded for in common DNA. It'd probably be that case that were males not to have nipples, there would have to be other more complex DNA sequences to down-regulate or turn off nipple production in the case of males.
From a Christian perspective, male nipples might just be explained by design economy in the genome. From a naturalist perspective, male nipples might just be explained by the fact that the bodies of both males and females are the result of (in the most part) activity of the same gene(s) (and probably that the genome would need to be more complex if there were to be other nipple-specific silencer genes in the case of males).
AMC
Delete"What is the distinction you are drawing between "how" and "why"? By "why", are you referring to "reasons" (in the sense of the outcome of mental deliberation or choice)?"
Thanks for the reply. To be fair, I wouldn't say it's necessarily a hard and fast distinction since one feeds into the other to some degree, but in context I was simply referring to the mechanism when I said "how". In other words, I think you described the mechanism by which males develop nipples, but I think Steve was addressing a more fundamental question.
"As a Christian (indeed calvinist), I agree that God has foreordained everything and that whatsoever comes to pass happens by virtue of God's reasons. However, if you are discussing the matter with a naturalist, then the naturalist will just reject posing a question in a way that assumes reasons are necessary."
On the contrary, I think the naturalist would give "reasons" they believe "necessary" for why they think males have nipples. These reasons could be subdivided into more proximal reasons (e.g. vestigial organs) and more fundamental reasons (e.g. chance and necessity a la Jacques Monod). As you said, we would strongly disagree with their reasons as Calvinist Christians, but still the naturalist does give reasons, reasons which they would argue are "necessary" on neo-Darwinian theory, even though we would argue their "reasons" are unreasonable.
"Apart from the X or Y chromosome, males and females possess the same DNA instructions for their body plans. It's hardly surprising, on naturalism, that males would have nipples because (although such nipples may not be advantageously functional) nipples are coded for in common DNA. It'd probably be that case that were males not to have nipples, there would have to be other more complex DNA sequences to down-regulate or turn off nipple production in the case of males."
1. Roughly speaking, that's true, but as I said the problem is you could say that about practically anything in our embryological development. You could always say it comes down to our DNA. But that's not saying anything that anyone would disagree with, per se, whether Christian skeptic of evolution or naturalistic evolutionist. In general Christians wouldn't argue against the role of genetics in our embryological development.
2. Also, as I previously mentioned, there's far more to embryological development than merely what the "DNA instructions" say.
3. But again, I think this isn't really responding to Steve on the level at which he addressed this question, I don't think. To put it another way, the Christian skeptic of neo-Darwinism and the naturalistic evolutionist could both agree males developed nipples in this fashion, but the Christian skeptic and the naturalistic evolutionist would disagree about the fundamental reasons why males have developed nipples in this fashion.
"From a Christian perspective, male nipples might just be explained by design economy in the genome."
DeleteWell, a theistic evolutionist could say the same. So I don't think this selects against let alone advances the argument against neo-Darwinism as such if that's your goal.
"From a naturalist perspective, male nipples might just be explained by the fact that the bodies of both males and females are the result of (in the most part) activity of the same gene(s) (and probably that the genome would need to be more complex if there were to be other nipple-specific silencer genes in the case of males)."
1. I think the Christian skeptic against neo-Darwinism could agree with this too. So again I don't think this is really saying anything against neo-Darwinism.
2. That said, respectfully, I think your scientific understanding about genetics here is too simplistic. It's not true that "the bodies of both males and females are the result of (in the most part) activity of the same gene". There's a host of other factors involved. Indeed, the central dogma itself is too simplistic in light of what we know today; there's not a straight line from genes to male/female bodies. That is, even if we look strictly at the genetics, gene activity and expression are influenced by a number of complex interacting factors (e.g. DNA methylation, transcription factors, gene promoter accessibility, the structural configuration of the chromatins). Also, I already mentioned the maternal hormones in fetal circulation which are arguably as significant as the genetics in the development of nipples. As such, even if there were one gene or a group of genes responsible for the development of nipples, though we know from cases like supernumerary nipples most aren't typically inherited (which would suggest genetic correlation), you can't simply "silence" these genes without it having significant ripples elsewhere in our development.