  Galaxy bias can be split into two components: a formation-bias based on the
locations of galaxy creation, and an evolution-bias that details their
subsequent evolution. In this letter we consider evolution-bias in the peaks
model. In this model, galaxy formation takes place at local maxima in the
density field, and we analyse the subsequent peculiar motion of these galaxies
in a linear model of structure formation. The peak restriction yields
differences in the velocity distribution and correlation between the galaxy and
the dark matter fields, which causes the evolution-bias component of the total
bias to evolve in a scale-dependent way. This mechanism naturally gives rise to
a change in shape between galaxy and matter correlation functions that depends
on the mean age of the galaxy population. This model predicts that older
galaxies would be more strongly biased on large scales compared to younger
galaxies. Our arguments are supported by a Monte-Carlo simulation of galaxy
pairs propagated using the Zel'dovich-approximation for describing linear
peculiar galaxy motion.
