  The complex spatiotemporal flow patterns in living tissues, driven by active
forces, have many of the characteristics associated with inertial turbulence
even though the Reynolds number is extremely low. Analyses of experimental data
from two-dimensional epithelial monolayers in combination with agent-based
simulations show that cell division and apoptosis lead to directed cell motion
for hours, resulting in rapid topological transitions in neighboring cells.
These transitions in turn generate both long ranged and long lived clockwise
and anticlockwise vortices, which gives rise to turbulent-like flows. Both
experiments and simulations show that at long wavelengths the wave vector ($k$)
dependent energy spectrum $E(k) \approx k^{-5/3}$, coinciding with the
Kolmogorov scaling in fully developed inertial turbulence. Using theoretical
arguments and simulations, we show that long-lived vortices lead to long-time
tails in the velocity auto-correlation function, $C_v(t) \sim t^{-1/2}$, which
has the same structure as in classical 2D fluids but with a different scaling
exponent.
