First, the link to the BBC article:

http://news.bbc.co.uk/1/hi/magazine/3472179.stm

Now, a few rebuttals:

>"But the science behind the film (Alien) is "beyond nonsense", according to Mr Cohen.

The idea that a creature would wait 12,000 years before hatching its egg, "without something eating it" is absurd, he says. That it would adapt instantly to the human immune system is similarly far-fetched."

According to the movie, parts of the spaceship were still working, the blue light shining over the eggs, for example, that Kane breaks as he acidentally falls into the pod area. From the movie, these eggs were part of a delivery that never went through. The delivery didn't go through because one of them hatched and killed the hapless alien pilot.

Why the pilot had such dangerous eggs as part of it's cargo suggests that the animals were some type of domesticated beast. Actually, anything can be imagined. What's important to remember from this, however, is that the aliens were not part of the planet/moon LV-426. They were a caargo from a spaceship that crashed there. The planet's atmosphere is primordial; the alien eggs aren't part of the ecosphere; and if there are any lifeforms on LV, they wouldn't eat the egg pods because they aren't evolutionarily adapted TO eat the eggpods or their contents. (* for a caveat)

As for the aliens "instantly adapting to the human immune system - it didn't need to. It was inside the stomach, not the bloodstream. Also, the face-hugger spent a small amount of time preparing Kane's body to accept and protect the egg. In other words, the facehugger is adaptable to a wide range of life forms, but needs time to change alter the DNA of the parasite so that it can grow within the host. All scientifically plausible.

As for how such a wonderful creature could come into being in the first place, there are at least two scenarios:

1. (*here comes the caveat) The Alien existed on a planet where more than one possibility for life arose, lived, and thrived, say, both carbon based and silicone based. This is not impossible, and both would have the bare basics for any and all subsequent parasites. The fact that it didn't work out that way on earth doesn't cancel out the possibility.

2. They were genetically created to feed off of as wide a food base as possible. But anything that can be genetically created in the lab - and be stable - carries the possibility of being created in nature.

NEXT

>"But the famous scene where the alien creature emerges from John Hurt's stomach is the most unrealistic of all.

"If you have something much bigger than your heart moving around inside your chest and you don't know about it, you are in big trouble."

It's easy for you not to know about it. Think of an 8 foot tapeworm living in your gut - chest cavity area. Except for a constant hunger, most people don't realize it is there. The longest tapeworm ever recorded in a human was 33 meters (108 feet!). The tapeworm lives quite comfortably, for months and years, with your immune system, without adversely affecting said immuune system. Since the baby Alien was probably no more than 3 feet, I'm guessing that this is, too, a possibility.

So anyway, when SF writers try their hand at imagining what Aliens would look like, I'd suggest that before they rule something out, they first think about what exists on our own planet first.

That said, I like Jack Cohen, he's a good writer. Though, like all humans, isn't infallible.