Bat milk

Capt'n Midnight

http://www.batcon.org/batsmag/v13n1-7.html

SURELY ONE OF THE MOST startling discoveries reported about bats ... was that some males can lactate like females, proving once again how little we know about the lives of bats. The lactating males are Dayak fruit bats (Dyacopterus spadiceus), a little-known, small flying fox of Malaysia and Borneo.

Milk production in males has never before been reported in wild animals. Thus far, it has been seen only in some highly inbred domestic animals and human males with tumors, those undergoing hormone treatments, or babies at birth. Even in these instances, it is extremely rare. In the case of Dayak fruit bats, the males have the correct plumbing and physiological capability to lactate, but the scientists don't yet know what it means. Although the males produced milk, their mammary glands and nipples were not as large as females, and the amount of milk was only about a tenth of that produced by females. Males were not observed nursing young.

The researchers note that if Dayak fruit bats prove to be monogamous, a mating system found in only about three percent of mammal species, their ability to lactate would make sense. Monogamous mammals share in the raising of their young. Only five bat species* are believed to form monogamous pairs, but it is not known whether any males of these species produce milk.

BTW how true is this bit ?
"monogamous, a mating system found in only about three percent of mammal species,"

John

Capt'n Midnight wrote:

BTW how true is this bit ?
"monogamous, a mating system found in only about three percent of mammal species,"

That sounds about right. I can't even think of any monogamous mammals. Sure in humans there was a study (or studies) that showed a high proportion of babies being raised by couple were fathered by another man (and obviously not to the knowledge of the "father").

Faith

Dolphins are monogamous, aren't they? There's definately at least one other mammel...

secret_squirrel

Swans and Wolves mate for life.

DrIndy

The interesting thing about primates including us is the difference between males and females in size and build. In strictly monogamous species like gibbons, the males and females are indistinguishable in size and build.

Gorillas however who have a harem of several females with one male have silverbacks who are twice or more the size and weight of females to fight off rivals.

Human males are on average 8 inches taller than women.

Go figure!

Capt'n Midnight

DrIndy wrote:

The interesting thing about primates including us is the difference between males and females in size and build. In strictly monogamous species like gibbons, the males and females are indistinguishable in size and build.

Gorillas however who have a harem of several females with one male have silverbacks who are twice or more the size and weight of females to fight off rivals.

Human males are on average 8 inches taller than women.

Go figure!

The difference in genetalia is even greater. Chimps are promiscious and for their body size have much larger testes than gorillas, we are about half way in between.

If anyone ever uses the old "what winks and makes lve like a gorilla ?" line, remember that gorillas are not very well endowed and even then IIRC they require a bone to do even that !

John

secret_squirrel wrote:

Swans and Wolves mate for life.

Swans aren't mammals. As far as I remember, monogamy is far more common in birds than in mammals.

Capt'n Midnight

John2 wrote:

As far as I remember, monogamy is far more common in birds

Hoggamous, higgamous,
men are polygamous.
Higgamous, hoggammous,
women, monogamous.



http://www.newscientist.com/article.ns?id=dn8429

The brainier male bats are, the smaller their testicles, according to a new study. Researchers suggest the correlation exists because both organs require a lot of energy to grow and maintain, leading individual species to find the optimum balance.

The analysis of 334 species of bat found that in species where the females were promiscuous, the males had evolved larger testes but had relatively small brains. In species, where the females were monogamous, the situation was reversed. Male fidelity appeared to have no influence over testes or brain size.
...
“An extraordinary range of testes mass was documented across bat species - from 0.12% to 8.4% of body mass. That exceeds the range of any other mammalian order,” says Scott Pitnick, from Syracuse University in New York, US, one of the research team. Primate testes vary between species from 0.02% and 0.75% of body mass.
...
Pitnick and his colleagues had predicted that, in species with promiscuous females, males would require bigger brains in order avoid being cuckolded. So they were surprised to find the opposite: “Perhaps monogamy is more neurologically demanding.”

8.4% of body mass :eek:

http://www.neoteny.org/a/testiclesize.html

Let us now apply this prediction to man. For an ape, man's testicles are medium-sized---considerably bigger than a gorilla's. Like a chimpanzee's, human testicles are housed in a scrotum that hangs outside the body where it keeps the sperm that have already been produced cool, therefore increasing their shelf life, as it were. This is all evidence of sperm competition in man. But human testicles are not nearly as large as those of chimps, and there is some tentative evidence that they are not operating on full power (that is, they might once have been bigger in our ancestors): Sperm production per gram of tissue is unusually low in man. All in all, it seems fair to conclude that women are not highly promiscuous, which is what we expected to find."