This is what I made this weekend, with the aid of some very cold weather. I can’t wait till I am able to start building snow forts - will it just snow already?
I was asked the following question:
- What is the evolutionary advantage of deciduous trees turning “beautiful colors” as their leaves prepare to fall
- What is the evolutionary advantage for humans to develop an appreciation for those same “beautiful colors”?
- How does it benefit us and our survival as a species to appreciate beauty?
Here is my response:
First, from the perspective of the trees:
The tree’s primary concern is the conservation of energy. As light becomes scarce the balance of energy shifts to the point where it costs the tree more in energy to maintain the leaves than is replenished by conducting photosynthesis. So, the tree evolved to cut it’s losses and go dormant until sunlight becomes more abundant. It is in this process of course that they turn “beautiful colors.”
Why? Well, the concept is more simple than one might think - as is the case with many evolved adaptations. The leaves are green because of chlorophyll, which absorbs very energetic wavelengths of light (blues) and low wavelengths of light (reds) and reflects the middle ranges (greens). [Side note: you can always tell the relative depth that a piece of seaweed originated from due to it’s color. If it is green then it came from near the surface, if it is red then it came from a deeper zone. This is because only high energy wavelengths of light reach it down there, and so it never evolved to absorb red light, which is low energy. So when we see it in our light conditions, it looks red, because it is reflecting all of that unabsorbed red light.]
One of the primary ways for new genes to evolve begins with an initial mistaken duplication of a gene - so imagine you have a gene for creating chlorophyll, which absorbs a specific range of light wavelengths. This gene gets duplicated by mistake, so now there are two. At a later point one of these genes undergoes a mutation, which causes it to absorb/reflect slightly different wavelengths of light. Repeat this process several times, and you end up with multiple pigments which absorb/reflect varying wavelengths of light. This of course is selected for by natural selection because those plants who inherited these mutant genes are better at absorbing energy from the sun, as they have a broader palate, so to speak.
When the light becomes scarce and the tree begins to cut it’s losses the chemistry works out so that the green chlorophyll die before many of the other pigments. These pigments that you see in the fall are there all the time, they are simply covered up by the ubiquitous green pigments. Some pigment reactions are less dependent on the light than others, and of course some plants evolved different pigments than others. Variable sugar concentrations can also have an impact on pigment concentrations at different times, and the temperature impacts chemical reaction rates.
So, in the end the tree did not evolve to have beautiful colors at all, but evolved pigment molecules which absorb multiple variable wavelengths of light - which we perceive as color.
Next, from the perspective of humans:
The simple answer is that appreciating fall colors as beautiful yields absolutely no added survival benefit to humans. So the question then becomes, why DO we appreciate them if it isn’t beneficial? I think that the answer lies in unintended consequences. The ability to see color is obviously highly valuable for our survival, as is our tendency to visually seek out contrast and variation. Those ancestors who paid little attention to brightly colored things may very well have missed out on some key warning signs given by poisonous animals or plants.
The fact that other things DID specifically evolve bright colors as beneficial adaptations (in contrast to the tree leaves) is a whole fascinating subject in and of itself. Generally speaking this lends itself to the “don’t mess with me, I’m tough” strategy. If I can be brightly colored, and thus highly visible to predators, yet still survive and reproduce - then I must have very good genes indeed. And you would do well to avoid me, especially since those ancestors of yours who did not are no longer around to propagate their careless ways. Of course this also lends itself to mimicry of warning coloration, which requires a statistical balance between mimics and genuinely dangerous species in order to remain effective, but that’s a story for another time.
The point is that color can be adaptive in many ways, and these adaptations generally fall into two categories: stay away from me, and come hither. As you rightly pointed out, there are many features of humans which we have evolved to find attractive, and good coloration is certainly one of these things. We are quick to notice when someone is “looking pale” and not feeling well. Color is information, to be compiled with the numerous other indicators of health and, ultimately, strong genes.
So, we could notice vibrant tree color because we evolved to pay attention to bright color as warning signs. We could notice it because we evolved to pay attention to bright color as indicators of health. More likely is that it is a combination thereof. However, this does not quite answer your question.
The true heart of the question, I think, is not why we notice and pay attention to these things, but why we find them beautiful. What is it about fire red and sunset orange that stir emotion in us? Why do we paint these things simply for the pleasure of looking at them? That is a more difficult question to answer, because it isn’t obviously a direct result of survival. This is a situation that evolutionary biology calls “co-opted genes.” This is a case where useful genes which are adaptive have additional impacts which are neutral in terms of survival. In terms of appreciating beauty I’m actually going to refer you to an interesting article in Scientific America here: http://www.scientificamerican.com/article.cfm?id=the-neuroscience-of-beauty
One quote from it, “Human neuroimaging studies have convincingly shown that the brain areas involved in aesthetic responses to artworks overlap with those that mediate the appraisal of objects of evolutionary importance, such as the desirability of foods or the attractiveness of potential mates.” In essence this effect is a result of extending the tools of one system into another. It has been suggested that religious faith occurs through much the same process, but I won’t get into that here. Let me know if you’re interested in that topic and I’ll write it out.
In the end our lives are filled with unintended consequences of adaptive genes. Why did we evolve to enjoy roller coasters? We did not, we evolved a positive response to epinephrine, which is released when we ride on roller coasters.
Please let me know if you have more questions about this - there are books and fields of study dedicated to these questions and so obviously this little sample is not comprehensive. Also feel free to ask questions about other evolutionary processes, this is my favorite area of study after all! I’ve recently written papers and/or had debates about the following: The evolution of morality and ethics, the consequences of controlling future genetic variation in humans through genetic engineering, the evolution of religious faith, and of course the staple debate: Evolution vs. intelligent design.
If you are reading this and disagree with any of my views,
I welcome a respectful discussion about it.
Oklahoma governor orders the halt of all military spouse benefits at state run posts in order to keep benefits from same-sex spouses.
As an American, this makes me ashamed of my government.
As a military spouse, this makes me furious.
Do you know any LGBT individuals in the military, or their spouses? If so, please share their experiences with discrimination based on their sexual orientation and/or gender identity. This is an important and prevalent issue, one which deserves our awareness of it. Thoughts?
With a vote of 61-30, the Senate voted to move forward on legislation that would prohibit workplace discrimination on the basis of sexual orientation and gender identity.
The vote Monday opens the floor to debate on the bill and the Senate is expected to schedule a full vote by week’s end. Click the photo for more info.
Have you experienced workplace discrimination based on your sexual orientation or gender identity? Did you learn anything from that experience which could help others in a similar situation?
Thanksgiving is on it’s way, and Christmas will be here before you know it. With many people making travel plans, I thought this might be informative. The prospect of dealing with screening and scanners at the airport is never fun, I know! I remember traveling home to the US from Belgrade, Serbia following my metoidioplasty - despite the pain and discomfort, the most stressful thing was worrying about the TSA bothering me about bandages, etc.
In any case, the link above states their policy. It isn’t great, but at least it exists. Chances are you’ll go through the process and nobody will know, but even if they do, you are not the first transgender person they will encounter. Just be informed about your rights, and remember that being polite can save you a great deal of grief.
Does anybody have any travel tips they’d like to share?
This occurs in 1/2000 humans When parents and doctors decide to “choose” a gender for the child, often surgically altering them so that they fit in this chosen gender role better, they quite often get it wrong.
Please don’t make a decision like this for another human being, please do not surgically alter a child so that they fit in better. Your intentions may be absolutely in the best interest of the child, but a great deal of research has shown that deciding this on their behalf is NOT in their best interest. Allow them to make the decision on their own as they grow up. Allow them the freedom of expression that every child deserves.
I’m proud of Germany for helping to rid the world of a stigma against people who don’t fit perfectly into the gender binary.
For more information: http://www.bbc.co.uk/news/world-europe-24767225
To my readers: What are your thoughts on this policy? Should it be adopted in other countries? Would you make any refinements/changes?
Last night we attended a conference hosted by the Center for Inquiry. Bill Nye was there speaking about the importance of advocating for good science education (especially for children) and the importance of investing in scientific research.
One of the reasons I was excited to attend this conference is because I am so concerned by the attitude towards science these days. Every day we use things which were created using physics, mathematics, chemistry, biology, etc. and yet people consistently deny the conclusions of these scientific fields.
Since I’m a biologist I’ll focus on my field, and state this simply: Evolution is a fact, natural selection is the theory of how this process occurs. If you are ever faced with the assertion that it is “just a theory” and so can be dismissed, kindly ask this person if they are also prepared to take on the Theory of Gravity and the Theory of Electricity.
Also point out to them that if evolution does not occur, they never need get another flu shot again. If the flu virus isn’t evolving, then the immune response caused by last year’s flu shot will protect them indefinitely.
If you have any questions about evolution, or science in general, or questions about how to inform people about science, please “ask” me, and I will answer you. This is vitally important - we have serious challenges to face, and we need a scientifically literate and aware population to face them.
After many long years, I have my piano once more.
It’s amazing how natural the keys still feel beneath my fingers.
A 2-minute preview of the film “God Loves Uganda” - about the impact that evangelicals are having in Uganda, where they helped propose a bill which would seek the death penalty for homosexuality.
7 LGBT Issues That Matter More Than Marriage
(Good, brief article - just click on the photo)
Recap: Marriage equality is incredibly important, but there are many other issues which profoundly impact our community, and require our attention.
Question for you: Rank the top 3 LGBT issues which you think are the most important (I’ve enabled answers, so please share your thoughts!). Where should we most focus our time, energy, and resources?