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“It’s a magical world, Hobbes, ol’ buddy… Let’s go exploring!”
Indians today can hardly recall the last time that they saw a vulture. In the 1990s, these majestic birds were a common sight in the subcontinent, and would show up wherever there was exposed carrion. As a child, I remember marveling at vultures circling at impressive heights, probably looking back down at me with their incredible eyesight, their wings outstretched as they effortlessly hovered on columns of warm air.
But since the nineties, their numbers have been falling dramatically in India, Pakistan and Nepal. The scale is astonishing – for every thousand white-rumped vultures in 1990, only one is alive today. A similarly sad story holds for the Indian vulture and the slender-billed vulture. Together, all three Asian vultures are now listed as being critically endangered.
The White rumped vulture, Gyps bengalensis
So what’s going on? It’s not that they are being hunted. For one thing, the killing of all wild animals in banned in India. But also, vultures have always provided a much valued ecological service. Most villagers dispose of dead animals by dumping the carrion. And they rely on the vultures to clean up.
Vultures have an undeservedly bad reputation. Because we associate carrion with disease, people believed that vultures spread diseases. But in fact, we now know that the opposite is true. Their powerfully corrosive stomach acids allow them to safely digest carrion that would be lethal to other scavengers, wiping out bacteria that can cause diseases like botulism and anthrax. They are the purgers of death and disease.
In their absence, populations of feral dogs have exploded, bringing with them the threat of rabies and human attacks. And if rats follow suit, India would face a new public health nightmare as it tries to control the spread of rodent-borne diseases like bubonic plague .
Meet Alice. She is 4 centimeters tall and moves about on wheels. Her goal in life is to look for food. Remarkably,the foraging behavior of this tiny robot has not been programmed by humans. Instead, her creators gave Alice a brain, and let evolution do the job of programming it. And Alice is going to show us why it is that individuals often make sacrifices for each other.
Animals often behave in seemingly selfless ways. The most regimented examples come from the social insects – the ants, termites, wasps and bees. Here selflessness is built in to the fabric of their society, as there are sterile castes of workers who tend to the eggs of the queen. Worker bees will often make the ultimate sacrifice and die protecting the hive from invaders. These are all altruistic acts, as they harm the individual while benefitting someone else.
A sweet deal? That's not a drop of honey, but in fact it's the engorged abdomen of the honeypot ant. These ants are used by the rest of the nest as living storage pots.
Take a moment to think about this behavior from the point of view of evolution. If everyone’s competing to get ahead, why take an unnecessary risk or suffer to help someone else? You really couldn’t do much worse than adopt a sterile lifestyle – it’s an evolutionary dead end.
People used to talk about such altruistic behavior as being ‘for the good of the species’. But this explanation does not work. Natural selection does not operate at the level of species, it is solely concerned with the reproductive success of the individual. Any gene that inclines an individual to be more concerned with the welfare of the species than with their own welfare is not going to get very far.
This type of evolutionary logic paints a picture of a world red in tooth and claw, one where you need to constantly be watching your back. But if everyone is looking out for their own selfish interests, where does selflessness come from? The solution to this puzzle was put forward by J. B. S. Haldane in the 1930s, and made precise by William Hamilton in 1963. Hamilton had the remarkable insight to think of this as an economics problem, and rephrase it in terms of costs and benefits.
An eyeless Mexican cavefish. If you think it looks sleepy, read on.
Out of the approximately 3 billion letters of DNA that make up your genome, there are about a 100 letters that neither of your parents possess. These are your own personal mutations. The machinery that copies DNA into new cells is very reliable, but it is not perfect. It makes errors at a rate equivalent to making a single typo for every 100 books filled with text. The sperm and egg cells that fused to form you carried a few such mutations, and therefore so do you.
Every child who grew up watching cartoons like X-men or the ninja turtles associates mutations with superpowers. But the sad reality is that, somewhat like a double edged sword, mutations are more likely to hurt you than do any good. Imagine if you were to change a few letters at random in a book. Chances are, you are not improving the story. A typo doesn’t usually do much. It’s easy to overlook and doesn’t change the essential meaning of a sentence. This is the idea of the neutral theory of evolution, that most mutations have little or no effect on the organism. While this may be the case, the rare events pack quite a punch. Beneficial mutations are rare, but they are the only road through which organisms become better adapted to their environments.*
Changes to DNA are more likely to be disruptive than beneficial, simply because it is easier for changes to mess things up than to improve them. This mutational burden is something that all life forms have to bear. In the long run, individuals that carry harmful mutations will, on average, produce fewer offspring than their peers. Over many generations, this means that the mutation will dwindle in frequency. This is how natural selection is constantly ‘weeding out’ disruptive mutations from our genomes.
There is a flip side to this argument, and it is the story of the blind cave fish. If a mutation disrupts a gene that is not being used, natural selection will have no restoring effect. This is why fish that adapt to a lifestyle of darkness in a cave tend to lose their eyes. There is no longer any advantage to having eyes, and so the deleterious mutations that creep in are no longer being weeded out. Think of it as the ‘use it or lose it’ school of evolution.**
I just bought an Arduino, which is a cheap open-source electronics board. You can program it from your computer and build all sort of interesting devices that can respond to their surroundings. It can take as inputs pretty much any kind of electronic sensor you can get your hands on (light, temperature, pressure, sound, force sensors, and countless others) and can use them to drive motors, switch things on and off, make music, run a web server, play pong, and so on. I just started tinkering around with it and it’s incredibly liberating to be able to get a computer to do something physical.
While looking around for interesting Arduino projects, I came across this incredible video via Make magazine. It’s an episode from a show hosted by Sylvia, a 9 year-old tinkerer and Arduino hacker.
There’s something irresistible about pop music. Every few months, a song is born that transcends cultural differences and plants itself into our minds. Many of us manage to resist the allure of pop through indifference or stubborn determination. Among the humpback whales, however, keeping up with the latest musical fads is a matter of survival.
Humpback whales use their immense bodies as resonating cavities to produce a truly impressive vocal range. A single male has a range wider than any human choir. They can sing from two octaves lower than a bass singer, to three octaves higher than a soprano. This whale choir broadcasts across the ocean, their songs travelling along for thousands of kilometers. Only the males sing, and they do so only during breeding seasons, suggesting that it plays an important role in attracting a mate.
And just like the songs that we listen to, the songs of the humpback have a precise musical structure. They can be broken into separate themes, each of which contain a number of phrases. Each phrase in turn contains a series of notes, ranging from chirps, bleeps and squeaks that sounds like something from a science fiction movie, to more gravelly grunts and a kind of deep, majestic roar. (Audio samples below)