SOMEBODY GET ME A DOCTOR...who knows evolution ;)

I think EVERYTHING should be looked at under the microscope of evolution. I think we could come up with better air conditioners, cars, medicines...hell, everything could be better if we approached from a "natural selection" attitude.

Answering the question about medicine needing an evolutionary prospective...I do. I often times think that we (humans) look to much into the short-term and not into the long. By looking at WHY human immune systems react the way they do, not just HOW they react may lead to better methods of dealing with illness. The first thing I would like to see is a shift away from the stigma attached to evolution education. The story about some med students complaining that evolution was "forced on them" is sad. Some aspects of ecology are uncomfortable for me, but as a scientist I explore them and try to gain an understanding. Avoiding evolution, or demonizing it, must not lead to a well rounded scientific mind. I would love to know if my doctor had any kind of evolutionary education before I become a patient. If more people understood evolution, I'm betting they would too. So, education becomes priority number 1.

Understanding human past (and disease past) seems crucial to certain situations. I think doctors could better prescribe less invasive treatments, or more natural ones, if they have an understanding of WHY humans react like they do...take the breast cancer example. As a high school teacher, I shudder at the idea of teens becoming pregnant as a method for fighting breast cancer (not to mention the economic and environmental impact of all those babies!), but knowing how humans evolved could lead to better PREVENTATIVE measures over time.

I think dealing with common ailments like cough and fever might be better handled if doctors AND patients had more knowledge about WHY cough and fever are beneficial. However, we live in an "immediate cure" world and patience and time aren't things we value (some of us do...but many in society want it NOW).

As for the analogy, I WOULD want my mechanic to know the history and evolution of the car I have. Perhaps the older model had a better solution for a problem that the mechanic faces now. If the mechanic understands the evolution of a system, perhaps (s)he could fix the problem quicker/easier/cheaper than if simply going on training. I'm not saying that you HAVE to have evolutionary knowledge to fix it, but it surely must be an advantage.

Here is an article on engineers using Darwin's principle of natural selection for designing analog circuits using Genetic Algorithms. Kinda advanced for my knowledge base of electronics, but I hope it makes my point that everything could be made better through evolution!

www.mrc.uidaho.edu/~knoren/GAs/B-159_paper.PDF

MOM...You mean that we came from MONKEYS?

What led to bipedal locomotion? Well, Africa is much different than it is today. The ancestors of "Lucy" or Australopithecus afarensis were most likely tree-dwellers in a more rain forest-like environment. However, Africa started to "dry out" and the rain forests were becoming more grassland. As the environment changed, so did our ancestors. There are many hypotheses on what happened at the forest shrank.

Some of these ideas include:

• Standing up to see over tall grass
• Pick fruit from trees
• Cool more efficiently (less surface area being warmed by the sun)
• Saves energy

As the forest changed, and the area between food patches increased, walking on all fours made it difficult to carry items (like food) and walking on two legs was "inefficient" for long distances, bipedal locomotion was a hell of a benefit.

Thus, walking on two legs saved the organism energy. And that gave our ancestor a competitive advantage. More food, more land coverage and more efficient energy usage is a huge advantage in the game of natural selection.

Now, for the brain size "thing"...I'm going off the reservation for this one. I feel like sharing some ideas that I have read before and some of my own (they are all starting to run together...). I think that our brain size is a direct response to the role of food. The powerful jaw of apes need an anchor point, and that anchor point would have restricted the amount of room that was available for the brain to expand. As diet changes, the need for the extremely strong jaws and different teeth start to disappear. As more protein is available, and the need for stronger jaws decreased, the brain has more room to expand. As food energy increases, more brain activity (which is very energy intense) is available.

I think that food drove evolution. But, I've been wrong before...and will be again. As I continue to read I'm sure that I will find more answers...or more questions. Deep, huh?

Out...

JBlack

On the Evolutionary Road...and other musings...

Dawkins warns of "a pair of temptations" in chapter 1. Those warnings were:

1.) historians are tempted to scour the past for patterns that repeat themselves.
2.) the idea that the past works to deliver our particular present is "the conceit of hindsight

Addressing #1: The idea that we can predict the future based on looking at events of the past may lead us to make mistakes and ignore what matters now. When addressing evolution (and especially human evolution), looking for patterns may point us in a direction that "misses the current point".

Addressing #2: The "conceit of hindsight" shows us how we (humans) think that we are the end-of-the-line for evolution. I think this is why (at least most people in the United States) are uncomfortable with human evolution discussion. In fact, only 4 in 10 Americans "believe" in evolution!

(http://www.gallup.com/poll/114544/darwin-birthday-believe-evolution.aspx)

Now that has a lot to do with evolutionary education (you'd be amazed at the number of colleagues that avoid the topic) I think that people are uncomfortable with the idea that all the steps of evolution weren't aimed at creating us. This makes people's heads hurt, and I've noticed that most people avoid what makes their head hurt. ;)

As far as the "mtDNA eve", the mitochondrial DNA of all humanity pinpoints the 'people' common ancestor in the all female line and "Y-chromosome Adam" is the equivalent in the all-male line. They are two out of a multitude of most recent common ancestors (MRCAs) that could be used to trace humans back. This answers the question of being the entire picture (it isn't).

Scientists use coalescent gene trees to help resolve the long-standing debate over human origins. The 'out of Africa' theory has many competing ideas over who, when and how many times humans left the continent (OOOA) and if we evolved separately once we arrived at a new destination (YOOA). However, based on the coalescent gene trees, we can be both descendants of a recent African exodus, and simultaneoulsy descen

Seriously...I will finish this later 'cause I've got students who expect me to answer their questions...the audacity!

Black

Try it yourself...

Hello kids...I'm thinking of using my high school kids as a "guinea pig" for playing with prisoner's dilemma. I just want to see how they do.

Anyway, I found a cool set of applets that let you simulate different kinds of prisoner's game theories. I spent more time at work messing with it than I should.

The link is...http://www.gametheory.net/applets/prisoners.html

Have fun.

Black

PS...am I the only one who has a different chapter 7 in Darwin? My chapter 7 is about instinct.

A Wednesday afternoon "TOOFER"

Hello kids...seeing as it is the middle of the trimester at school (work) and it is parent-teacher conferences, I will be doing a "TOOFER". That is I will be addressing two questions in this week's blog.

For those of you that are parents (or may be someday)...be nice to your kids teachers (especially at PTC time), we really aren't out to get your kids. Well, maybe some of them ;)

Anyway, let us discuss the question from the week our papers were due...

QUEENS VS. WORKERS:

Queens and workers...there is definitely a conflict between these two. Queen keeps a sister down by not letting her reproduce, yet sister has to help raise families that aren't theirs. However, there are instances where the worker bees may parasatize the next generation for their own benefit.

A recent study on bees in Brazil showed that worker bees are generally unable to mate, but are capable of laying unfertilized eggs which can develop into male offspring. To assure dominance over reproduction the Queen often selectively eats any worker laid eggs. In some species other workers may eat the eggs of fellow workers in what is known as 'worker policing'.

Even with these barriers there is much to gain for worker bees producing their own offspring, however the benefit is entirely for the individual and can be costly for the colony overall. The team found that workers who reproduce can live as much as three times longer, meaning that reproducing workers have a life expectancy almost matching the Queen herself.

This added life expectancy is thought to be because workers who reproduce do not usually carry out risky tasks such as foraging. However as worker bees who are reproducing are not working, an increase in individual workers who reproduce puts the collective production of the colony in jeopardy, hence a queen-worker conflict over the production of males ensues.

That sounds super technical...and it is. I found this information in the journal article: Alves, DA; Imperatriz-Fonseca, VL; Francoy, TM; Santos-Filho, PS; Billen, J; Wenseleers, T. The queen is dead-long live the workers: intraspecific parasitism by workers in the stingless bee Melipona scutellaris. Molecular Ecology, 2009; DOI:

So, who wins, loses and what are the consequences. Well, the worker that reproduces when the aren't "allowed" to is being selfish and benefits by gaining a longer life and having genes floating out in the world. The queen hurts due to increased competition and (according to the article) the colony can suffer as well, since all parts of the machine aren't working as they "should". It is a complex issue, and I can see where the selfish genes are really difficult to suppress.

Question #2 of your "toofer"...evolution of altruism, even in unrelated organisms...vampire bats in particular.

The background on this: Using the prisoner's dilemma, why do vampire bats share when they have a good night of hunting, when the best strategy for the individual seems like defecting? The way that I see it, is that if you are only facing ONE situation where you need to get some blood from a lucky bat, the best option is to defect. They payoff is very good and you don't reciprocate. However, in most cases, you aren't just living in a "one time" environment. You might not do well tonight, and someone helps you out. The next time you may have to help someone out. Even if you aren't related to that bat (according to the Wilkinson experiment in Dawkins) the others recognize who is an "old friend" and thus may hold a grudge (the grudger...from ch 10) and you are in danger of starving. Selfishness may be rewarded in the short term, but cooperation (in this case) seems to be a more effective strategy in the long term. You can't pass along genes when you are dead on the cave floor from starving!

A bit more info for the interested! From the website: http://brembs.net/ipd/ipd.html

Blood-sharing in vampire bats

Scientists working on cooperation among vampire bats (Desmondus rotundus) face the same difficulties in measuring all the essential parameters, but are in a somewhat better position. Some 8'%, of adult vampire bats fail to find food on any given night (Wilkinson 1984), but on such nights without a blood meal they are often fed by successful roostmates. This behaviour is vital for the recipients, since their energy budget leaves them 48-72 h of food deprivation before starvation (McNab 1973). Wilkinson (1984) showed that food sharing by regurgitation of blood "depends equally and independently on degree of relatedness and an index of opportunity for reciprocation". He suggested that w is probably high enough to fit the IPD due to the long lifespan of the individuals and the stable composition of groups in which the average coefficient of relatedness is comparatively low (0.08-0.11; Wilkinson 1988). Fig. 6 shows that b>c because the exponential postfeeding weightless enables a donor to lose less time to starvation by regurgitation of blood than the recipient gains. Hence, it is plausible that T>R>P>S. Furthermore, the cognitive abilities of vampire bats appear to be sufficiently well-developed to guarantee recognition of cooperators and defectors (Wilkinson 1984). While it is reported that bats do in fact deny feeding those roostmates that refused to regurgitate previously (i.e. act retaliatorily; Wilkinson 1984), it still remains to find out which strategy the bats actually use. An applicability of the IPD should be confirmed by further investigations.

Fig. 6. Predictive curve of post feeding weightlosses in vampire bats (Desmondus rotundus). A donation of 5% of pre-feeding weight when at weight D should cause a donor to lose C hours but provide the recipient at weight H with B hours. B >C for all E > F. See text for details. Redrawn from: Wilkinson, G. S. 1984. Reciprocal food sharing in the vampire bat. Nature 308: 183.

That is a lot for your "TOOFER" kiddies. Looking forward to input!

Black...tired and not ready to face parents.

Natural Vs. Sexual Selection

Natural selection allows individuals with certain traits to survive based on the conditions of the environment. These traits give the offspring of individuals a greater advantage of survival, and those alleles continue on with greater abundance as long as that trait provides an advantage BASED ON CONDITIONS. If those conditions are to change, and the adaptive advantage is no longer a benefit, individuals with that trait may no longer have the "upper hand". There is no choices made on the part of the individual, or the entire group. The environment selects what is an advantage, and what is not.

Sexual selection is driven by what is perceived as being advantageous by the one making the choice. In female African Cichlids, females can select for color based only on female choice. Speciation of this species of fish has been a result of both natural selection (feeding advantages, and adaptations allowing fish to fill niches) and sexual selection (color patterns, size etc. that may not always influence survival. In sexual selection, there is a choice made by individuals and that choice may impact the group as a whole.

Darwin states that certain evolutionary traits can be explained by competition within a species. Darwin defined sexual selection as the effects of the "struggle between the individuals of one sex, generally the males, for the possession of the other sex" I'm sure had Darwin met my wife, he would have chosen his "possession" wording more carefully...but what we have seen in class is many times the female actually chooses who she will mate with based on the display or "fitness" of a male.

Fisher later tied female selection to genetic control and natural selection. He said that it is easy to see (and later based on mathematics) that every baby born inherits genes that made the father attractive to the mother and also inherits the genes that made the mother attracted to the male. So there is a female choice aspect, AND a natural selection aspect to sexual selection. The genes in males don't manifest the desire for a trait, and females don't manifest the trait being selected for. (I learned this from a lecture given by Dawkins himself...I will post the link).

More to come...I've got to get to teach class now.

Ok...I'm back.

Anyway, here is the link to the Dawkins lecture on Sex Ratio and Sexual Selection: http://richarddawkins.net/article,1354,Lecture-on-Sex-Ratio-Theory-and-Sexual-Selection,Richard-Dawkins

It is around 30 minutes long and it covers quite a bit of what we are talking about in class.

Sex Ratio Redux...

The idea of sex ratio being an ESS is broken down in an easy to follow manner in W.D. Hamilton's work published in his 1967 paper: "Extraordinary Sex Ratios"...follow this link http://www.sciencemag.org/cgi/content/citation/156/3774/477

This is based on the assumption the condition that males and females cost equal amounts to produce:
1. Suppose male births are less common than female.
2. A newborn male then has better mating prospects than a newborn female, and therefore
can expect to have more offspring.
3. Therefore parents genetically disposed to produce males tend to have more than average
numbers of grandchildren born to them.
4. Therefore the genes for male-producing tendencies spread, and male births become
more common.

As the 1:1 sex ratio is approached, the advantage associated with producing males dies away.
The same reasoning holds if females are substituted for males through-out. Therefore 1:1 is the equilibrium ratio.

Fisher seems to have been looking at this from a parental expenditure standpoint.

Fisher's principle is an ESS because once it has been established in a population, it benefits those that "play by that rule" and punishes those who deviate from the ESS.

The sex chromosome assymetry is interesting, due to the fact that xx are homogametic and xy are heterogametic. Y should benefit, because XX never passes along the y chromosome, but x should benefit because the homogametic sex passing it along (but with only half the efficiency). The mitochondria (as well as some other non-nuclear genetics) can bias because they are only carried on through the cytoplasm of the egg. Other non-nuclear items causing bias are bacteria that may be "male-killers".