Malcolm MacIver has a posting in the Discovery Blog, Science not Fiction. (here) He connects consciousness with the evolution from marine animals to land animals. His argument goes: (1) marine animals cannot see far compared to their speed (2) therefore marine animals can only react quickly to what they sense (3) moving to land increased their ‘perceptual horizon’ 10,000 fold (4) therefore land animals had time to plan their actions rather than simply react (5) planning needs consciousness.

This puts the first such members of the “buena vista sensing club” into a very interesting position, from an evolutionary perspective. Think of the first animal that gains whatever mutation it might take to disconnect sensory input from motor output (before this point, their rapid linkage was necessary because of the need for reactivity to avoid becoming lunch). At this point, they can potentially survey multiple possible futures and pick the one most likely to lead to success. For example, rather than go straight for the gazelle and risk disclosing your position too soon, you may choose to stalk slowly along a line of bushes (wary that your future dinner is also seeing 10,000 times better than its watery ancestors) until you are much closer.

I am not sure I buy this picture, although it could be behind a big step up in consciousness. One problem is that the theory depends heavily on vision being the main sense. Cetacea (dophins, whales) were land animals that returned to the sea. They did not lose their consciousness but used their hearing as their main sense rather than sight. Their perceptual horizons may be as long or longer than ours. Marine animals use tactile sensing of water movements and electrical sensing as well. One would have to look at the perceptual horizon available from all senses to make a tight argument for the buena vista theory.

There is also the Cephalopods (octopus, squid, cuttlefish) which have never been on land but appear to have no problem with planning and the like. They would not have a same sort of consciousness as vertebrates but it is not a given that they lack a very similar function.

On the other hand, consciousness is costly and slower than reflex so it is not likely to be elaborated in environments where it does not give a yield greater than its cost. Read the post for some interesting crystal ball looks as well as the fuller explanation of the theory.