Science meets the web…

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Deep down inside we all knew that The Lord of The Rings Trilogy was based on Tolkien’s visit to an unreachable land and what he wrote was based on truth. What we didn’t know, however, is that Tolkien had mistaken Indonesia for Middle Earth.

Homo floresiensis, nicknamed the hobbit, is the biggest thing in Human Evolution at the moment. This 1 meter tall individual was found on the island of Flores in Indonesia. It is believed to be an off shoot of Homo erectus that was trapped on the island and evolved separately. Wild ideas of how the hominid achieved its small size have been tossed back and forth for some time now, but as of this month everything may have come to a resolution. Weston et al. published a paper titled: Insular dwarfism in hippos and a model for brain size reduction in Homo floresiensis. Basically, they cite the phenomena known as “Island Dwarfism” for the cause of these hobbits. Weird things are know to happen on islands from mini elephants to giant rats and now hobbits. When organisms are placed in an enclosed environment without predators, size becomes less of a factor for survival provided there is ample food.

Still, the main reason why Homo floresiensis is such a big deal resides in that fact that the fossils found are only 18,000 years old! Modern humans (Homo sapiens) are said to have diverged from Homo erectus 200,000 years ago. Also, if you ask the oldest members in the villages on Flores about the hobbit they will tell stories of little people who would run into town and steal their food.The ability of the hobbit to survive that long and past the split from Homo erectus may just throw off everything we know about human evolution. I, however, am still holding out for a hippogryph skeleton because I know J.K. Rowling is hiding something…

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Leon

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Kids have always been known to ruin the mood! From knocking at the door to screaming down the hall, kids have always gotten in the way of parents trying to get jiggy wit it. Research by a collaborative group of scientists (Burnham TC, Chapman JF, Gray PB, McIntyre MH, Lipson SF, Ellison PT) has pointed to another way in which “the children” may be disrupting the vibes. They found that males with kids had overall lower testosterone levels.

Burnham TC et al., 2003 & Gray PB., 2003

They relate this occurrence to males needing to invest time in their offspring once they are born. Reduced testosterone levels in the past may have helped males reduce their risky behaviors and spend more time at home. Their offspring may have had a greater chance of survival with dad around. So, next time you embark on an under the sheets adventure know that even if your kids are at grandma’s it may not help!

Leon

(In the graphs) The first graph is Burnham, TC  et al., 2003 and shows testosterone levels in accordance to whether or not the male is married and if he has kids. The lowest column on the left is a married male with kids. The second graph is Gray, PB, 2003 and here we see the same experiement, but with Swahili men of Kenya. Once again the lowest column on the right is married men with kids. One could also infer from these graphs that marriage lowers testosterone levels.

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For the first actual post, I decided to try and tie together some basic notions of reproductive ecology. Keeping things simple, lets start with energy. We won’t get into how energy is processed or where it comes from (food), but rather we shall save that for another post. With energy, an organism (and we will focus on humans here) can do three things. They can divert that energy to growth (growing vertically or horizontally), maintenance (helping repair the body or fight off infection), and  reproduction (getting freaky and everything that leads up to it). This makes up the building blocks of Life History Theory (as an organism progresses throughout its life the challenges they face will deal with managing energy in these three categories).

So whats with the title you might ask? Well to achieve this allocation of energy, men and women take very different routes. To begin with lets take men. Their main energy investment after growth, will be keeping themselves sexy and healthy enough to reproduce while also trying to survive. Women also have to do this (we will get into the differences between male and female life history stratigies in another post), but they have one other major cost that must always be taken into account, menstruation and the ability to carry a child! This takes up an enormous amount of energy.  In men, we find no amount of physical activity (ENERGY USE) can really affect their ability to reproduce. Bagatell & Bremner in 1990 tested all the major things connected with male fertility, in normal males and males that had been run to the point of exhastion. After looking at these two sets of men, they found nothing that could link physical activity to a reduced ability to reproduce.  When looking at women,however, this was definintly not the case.

Ellison in 1986, showed that even moderate exercise in females lead to a reduced ability to reproduce.

So whats going on here? Well for men, they do not have to invest a lot of energy into their reproductive mechanism, sperm. For women, however, they have to invest a very large sum of energy into the maintaining of their reproductive organs. There are some cases, however, when this can come in handy. As we saw with the runners, males stayed the same and women well their reproductive functioning was slightly altered. This  study, however, did not show long term effects. When looking at a society like the Lese of the Ituri forest, who go through hunger seasons, we can see the long term affects of our biological functioning.  With Lese men. who are constanly faced with less energy due to food availabilty one will see a reduced upper arm circumfrence or muscle mass. This is because they can not invest energy into maintaing muscle mass due to energy availability. Thus, the Lese men lose strength and size. The Lese women, however, can continue on like normal with no significant difference in their bodily composition. How? Well they just slow their reproductive functioning. By slowing their menstraul cycles and shutting down reproduction, they save a great deal of energy. This energy can then be used to support their existing mass. In the end we are left with two different energetic systems that can be explored even further. Also, I am left with school days song from annie get your gun, “Anything you can do I can do better; I can do anything better than you”

Leon

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Hey All,

Thanks for reading! I am starting this blog to launch myself into the blogoshpere. Also, I am trying to bring what I spend most of my time on, Science, to all of you out there on the interwebs. I deal mainly with hormones, so most of my posts will be built around my knowledge in this area. I will, however, try to infuse all late breaking science news into this blog. Thanks for reading and feel free to coment.

Thanks,

Leon

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