i can’t. My daddy was a black widow spider. 
Dawkins had a whole chapter on this subject, and IIRC he said roughly what Lemur866 said. I forget the book, it might have been “The Selfish Gene.”
Excellent explanation. Very clear, and not obvious to me prior to reading it.
The cite request was not for evidence that male organisms sometimes contribute parental care.
The cite request was challenging the assertion that in organisms where the males do not contribute to parental care, the sex ratio is not 1:1. But the notion is clearly false. Species where males contribute have 1:1 sex ratios, species where males don’t contribute (which is most species) have 1:1 sex ratios.
All these notions about how non-breeding males contribute to the group are a red herring.
Imagine you are a mother, and can choose the sex of your offspring. Do you chose to create a male offspring or a female offspring? Even if your species has a strategy whereby males serve as decoys, or insurance against disaster, what advantage is it to a new mother to create one of these sacrificial decoys? Mothers who create breeding offspring are represented in the next generation. Mothers who create decoys are not. Therefore, there is intense selection against creating decoys, and intense selection for creating breeding offspring.
The simple answer is that the more sex ratios deviate from 1:1, the more evolutionary benefit there is to create offspring of the less numerous sex. This requires no complex argument from group selection, or just-so stories about sacrificial decoys. It doesn’t matter that if the species were almost all female there would be almost twice as many offspring, what matters is how many offspring an individual female can have, and how many offspring an individual male can have. If females have more offspring than males, females are selected for. If males have more offspring than females, males are selected for.
Well, it does matter, in so far as group selection does occur. It’s just that the selective pressures for having an abundance of females are weaker than the pressures for equal numbers.
It could well be. This argument sounds familiar to me now, although I obviously didn’t remember it when i wrote the post. Excellent answers, thanks a bunch.
If the role of the females is to pop out calfs one after the other; the corresponding role that falls to males is to fight other males for the ability to cause that reproduction. Very simply, the evolutionary pressure on males (as decoys, cannon fodder or winners of head-butting contests) is to be the ones to win the hand (hoof? hindquarters?) of the female.
This is obvious in the resulting sexual differences; the males, under more pressure, tend to be larger and more aggressive. I suppose it’s an interesting exercise to decide what trophy hunting is doing to this - presumably you are selecting for smaller, more feminine males. (metrosexual mooses/meese?) A mutation for no antlers, for example, would be a significant survival trait.
In humans and similar mammals, the single pair is sufficient and necessary to raise a child; offspring need significant support even after birth for a while. In these cases, the male fights less - there is one female per male so odds of reproducing are better for all males, so less fighting and aggression is called for; wolves, for example, are not significantly sexually differentiated, but the male will hunt to feed the female and cubs. OTOH, in a grazing animal like moose, there’s not a lot of extra that a male can do to support the female, other than say “here’s some grass over here” and fight off the wolves - and chase away other males.
All great theories, but a species dependant on bisexual reproduction which does not produce males and females in comparable numbers is in danger of going extinct. Any catastrophe which kills half the population could easily kill all the animals of one sex if the proportions were on the level of 10:1. Some of our statisticians can work out the details.
Non-mammals have more complex reproductive strategies that allow variation in the proportion of sex, but mammals are stuck with the results at conception, and need something very reliable.
No. The explanation that many people have offered, which was made famous by R. A. Fisher, has long been accepted. Not only does it explain 1:1 ratios (of investment, not individuals), but it can be extended to explain other ratios that are found in special situations, such as some social insects with haplodiploid genetic systems.
Well aside from Fisher’s enormous contributions to the field, and the use of his principle in explaining other related phenomena, and the acclaim of so many other eminent evolutionary experts, what does he know about it?
I understand, but it’s not my only heretical belief. I was addressing the situation of great disproportion as described in the OP. But I suppose Fisher has decribed why that great disproportion would not exist within the normal selection process to start with.