These characters mean "Weak Meat Strong Eat" -- the weak are meat for the strong. It's a Chinese (and Japanese) saying. Sometimes it is even translated as "Survival of the fittest"!
One of the repeated themes in Cloud Atlas is: The weak are meat the strong do eat. David Mitchell, the author, lived in Japan for many years and has a Japanese wife. I suspect he learned this phrasing from the Japanese.
My favorite sub-plot in Cloud Atlas is the Orison of Sonmi 451. Hmm... what is psychogenomics? (See also Dune.)
Cloud Atlas: ... sourced his supply of psychogenomics theses from an obscure tech institute in Baikal. The original author of my x-postgrad’s work was a production zone immigrant named Yusouf Suleiman. Xtremists were killing genomicists in Siberia at that time, and Suleiman and three of his professors were blown up by a car bomb. Baikal being Baikal, Suleiman’s research languished in obscurity for ten years until it was sold on. The agent liaised with contacts at Papa Song Corp to instream Suleiman’s ascension neuro-formula to our Soap. Yoona939 was the prime specimen; I was a modified backup. If all that sounds unlikely, Hae-Joo added, I should remember that most of science’s holy grails are discovered by accident, in unxpected places.Some video of Suleiman (identified by caption) appears in the movie in the scene in which Hae-Joo educates Sonmi about fabricants and genetic engineering. Suleiman is lecturing in front of a board covered with equations -- no snail shells in sight.