Hacker News Reader

Comment by VLM | Hacker News Reader

Using blue-green algae was a bad decision in the fictional design. Its really old. There seems to be something of a "law" that if its technically possible, evolution, given enough time, will evolve it. Since it hasn't happened naturally in billions of years, its not going to work artificially because it surely already happened at least a couple times and didn't work in the long run.

Now pick a species thats "new" like humans, and give us something weird like direct atmospheric nitrogen fixing for our proteins, or photosynthesis, now that could have some interesting consequences. Or instead of us, horses, or mules, or domestic dogs or something.

View on HN

There are good reasons why evolution will never converge on many types of solutions to problems in many lineages in planetary lifetime timescales. Essentially, it's because future evolution is constrained by past evolution, and many complex solutions require diverse pre-adaptations that are precluded by accident. These are places where engineering beats evolution, and there's scope for us to make improvements on what nature has achieved.

Surface area to volume ratio of humans and other animals is way too small to allow anything interesting to come of us photosynthesising (e.g. see [1] for crude calculations). Although a healthy green glow would be nice.

[1] - http://hplusbiopolitics.wordpress.com/2008/08/12/photosynthe...

The writeup is pretty good, but I read an much older writeup which diverged in some ways:

1) The assumptions from the article I read long ago were you'd ideally have a topical UV sunscreen that magically gradually "infected" the skin, which wipes out both the UV problem and the application problem, and it would be cheap enough to distribute to war refugees, starving famine farmers, hurricane areas, that kind of thing. Temporary emergency rather than lifetime green glow. So depending on your math, laying around in the sun would only generate a couple apples worth of energy for a person. Not impressive for a hungry dude in Wisconsin in 2013, but a handful of apples is actually a pretty good day for someone in (insert every war torn drought famine area throughout the ages)

2) The article I read a long time ago was of a vintage where the jokes would revolve around Federation Starship Captain Kirk's paradise would be nude beach of skinny green skinned Orion women rather than Bruce Banner jokes.

3) There would be interesting sociological issues where if this was solely applied to poor people, their verdant green skin would be a nearly 100% effective way to discriminate for socioeconomic class based on skin color.

Exploring the social implications would make a pretty interesting sci-fi novel.

Why add the extra complication of painting a person green (safety, removal, efficaciousness). Why not just grow a slab of blue-green that excretes sugar and drains into a pot for the end of the day.

Load on the kidneys and yeast issues.

If its really sweet like honey, bees will go crazy. If its not sweet enough to attract bugs, there will be a lot of water drinking going on to the point of ridiculousness (like trying to gain weight drinking diet cola). If there's enough sugar to taste, yeasts will eat it resulting in lots of alcohol, and unfortunately yeasts are ridiculously tough.

So are you saying it would be possible to supply "lifepacks" to war / famine / disaster torn areas, of just enough to get by food, but we need to supply nets or flyswatters?

It's also silly because many blue-green algae (cyanobacteria), including those in rice paddies, already fix nitrogen in their heterocysts.

Reply on news.ycombinator.com