pioneer in the application of methods from information theory to the study of evolution, he designed the Avida system that launched the use of digital life as a tool for investigating basic questions in evolutionary biology. He is the author of the textbook Introduction to Artificial Life.
Adami applied the “Page 99 Test” to his new book, The Evolution of Biological Information: How Evolution Creates Complexity, from Viruses to Brains, and reported the following:
Page 99 in my book has two Exercises in it. Literally, it's part of the problem set at the end of the chapter "Information Theory in Biology". There are two exercises on this page: the first one asks you to do a number of calculations that allow you to derive the information transmission capacity of a class of channels that often arise in biology. The second exercise asks you to calculate the capacity of the communication channel that cotton plants use to alert a type of wasp that the pest (that is presently biting their leaves) is precisely the kind that the wasp likes to lay their eggs in. As you pick up your jaw from the floor ("Excuse me, plants don't talk!") let me explain. The plant does not like it that its leaves are being dined upon. What could it possibly do? It turns out that there are two types of "pests" (they are really caterpillars) that attack these plant leaves, and only one of them will actually, when injected with wasp eggs, bring forth larvae of the wasp (a highly unfortunate event for the caterpillar). Trouble is, the wasp cannot visually distinguish between the two, so in the absence of some helpful info, half the time its brood would be doomed. This helpful info: that's what the plant provides. The bite of the caterpillar includes a substance that is very specific to it. The plant's molecular system then synthesizes a terpene (an aromatic compound) that is specific to that particular bite. Terpenes (think turpentine) are not only highly aromatic but also highly volatile: you can smell them from far away. And so evolution has taken advantage of this situation: the wasp can distinguish the different smells released by the bitten leaf (whether it was bitten by the preferred, or the decoy, herbivore), and will then only lay its eggs in the type that will bear its offspring. Thus, the plant signals to the wasp: "this one here, put your eggs into them" (so that the bugs may die and stop eating my leaves). In Chapter 3, enough data is given to the reader that they can calculate that about a third of a bit is sent to the wasp by the plant, but this is already sufficient so that the wasp selects the correct target about 80% of the time, which is a vast improvement over the 50% you would get in the absence of the herbaceous hint.Learn more about The Evolution of Biological Information at the Princeton University Press website.
So is this exercise emblematic of the whole book? In some ways yes, in some ways no. Yes, in the sense that there is math in the book, and that you can use this math to calculate information, and in the sense that even though this is only a tiny example of how information is crucial to all living things, it is a good example: information is used to gain fitness, to make more offspring. The better your ability to discriminate between good and bad (for you), the more offspring you'll have. You might immediately ask: "But if this is true, why only 80%, surely getting a full bit (thus giving 100% accurate discrimination) would be even better? The answer to this is yes, but there are diminishing returns. It turns out that there is enough information in the signal for the wasp to distinguish perfectly (in theory). The bottleneck is in the wasp's smell: to make it a more accurate detector would require a significant "investment" in more complex molecular machinery. At some point, the cost outweighs the benefits. I would wager (even though this has yet to be proven) that the 80% accuracy is just at the point where no net gain (in overall fitness) is possible.
No, in the sense that the book's themes are far grander than the information exchanged between living things. In my book, I discuss how information allows you to understand every facet of biology better: how information about the world an organism lives in is a good measure of the complexity of the organism, how this information grows (on average) during the evolutionary process, how information is used by organisms (including animals and ourselves) to cooperate, and how information processing is crucial to understand intelligence (chapter 9). I even outline (in chapter 7) how information is key to understanding how life may have arisen in the first place, and how cancer is basically the outcome of a "failure to communicate" (chapter 10). So, page 99 gives a good glimpse of the book, but an imperfect one. It is a set of mathematical exercises, but only a bit more than half the chapters have math. It is about information in biology, but the book's scope is far grander: it tries to make the case that (to borrow a well-known line) nothing in biology makes sense, except in the light of information.
--Marshal Zeringue
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