Arik Kershenbaum assumes that evolution is Universal (he gives reasons). E.g. So alien animals will have legs of some sort but they might be made up of different biological compounds, be different in number and look different from Earthling legs, but they will still be legs used to move the animal around, either to catch prey or escape prey, because having alien life that isn't either prey/predator is an impossibility (because that's how evolution works
). Apparently slime aliens won't be able to move around fast enough because snails and slugs don't move fast enough (there are physics reasons for this but he doesn't go into that). So far, so good. But it gets more abstract and waffley as communication, language (only humans have language!!
) and the more social aspects make an appearance. He also leaves out fungi and slime molds. The slime molds turn a fair number of the authors arguments on their head. He does point out several times that he is not sure DNA is universal, but doesn't bother to come up with anything else that has a same/similar function to DNA. RNA (from what I've read) is not particularly robust, which is why it was replaced with DNA. He also states he doesn't know if aliens have sex. Only evolution doesn't really work if there is no exchange of genetic material - otherwise you just have clones. He also assumes carbon is the building block of life but doesn't bother to say why (there are reasons why carbon would be a good choice, but it doesn't have to be the only choice, only Kershenbaum doesn't explain any of that). In short, the topic is interesting, but Kershenbaum doesn't really explore it properly. The book comes across as too anthropocentric and I suspect the author lacks imagination. There is no mention of aliens having opposable thumbs. Wouldn't you need opposable digits or multiple tentacles to build starships? This book is more a simplistic summary/overview of earth ecology than anything else, and then a few paragraphs "explaining" that it
must be the same on other planets. So fairly disappointing if you were expecting something more than what you learned in a high school biology class and from watching Star Trek. In short: Life on other worlds will be like ours, but different. Intelligent life will be similar to humans, but not.
I wouldn't be the least bit surprised if Kershenbaum's book was a prescribed book for his first year collage class in the hopes that sticking some mention of aliens in the title and text will make his students want to read it. Helpful hint: The epilogue summarises the whole book in point form.
A better book on a similar subject is
The Equations of Life: How Physics Shapes Evolution, by Charles S. Cockell. This book is more physics based, than biology based like the Kershenbaum book, but I think Cockell explains his reasoning better.
PS: Evolution isn't an anthopogenic personality/entity. It doesn't decide or try anything. The ability of a particular species to evolve in particular ways is limited by the genetics of it's ancestors. E.g. That's why all mammals have 5 digits (unless lost like horses) on the ends of 4 limbs. There were ancient fishy creatures with 6, 7 or 8 digits but their progeny didn't make it onto land, and didn't evolve into all the land animals. Giraffe's don't have extra vertebrae in their long necks (compared to other mammals), they just have bigger/longer vertebrae. Imagine if humans evolved from starfish as opposed to fish. Humans would be radially symmetrical, have 5+ arms and however many digits, or maybe tentacles would be more useful? Multiple eyes? Eyes are useful, they evolved several times.
Sorry about the rant. Looks like this book pissed me off more this morning, than it did last night.