Tweeting,
chattering or squawking is a choice open to some birds. A relatively few can
learn to vocalize. Parrots, mina birds and the little zebra finch are examples.
To be vocal takes a big frontal brain lobes and in humans this part of the
brain matures later than the other parts and it turns out that the same is true
for vocal learners amongst the birds.
The
question that was keeping Chen et al
up nights was this an evolutionary trait that was programmed into the cells, or
was this dependent on interaction with the surrounding cell. One way to find
out is to mix and match and this was the experiment. They, used zebra finch and
Japanese quail eggs, an array of sharp knives and syringes and manufactured some
finch/quail chimeras (1).
The
part of the brain that develops into the frontal lobes is known as the
telencephalon and it was this part of the early finch embryos that was used to
replace that of the quails. Then one has to wait.
In
the fullness of time the chimeric brains were developing well and these brains
were examined along with brains of normal donors and hosts. Although the
species diverged as long ago as 65M years the chimeras were working in the egg, but didn’t hatch.
In
the chimera, the telencephala grew larger than in finches, but was smaller than
quails. The conclusion of the study was that cell autonomous (evolutionary
control) and cell-interdependence were both involved.
With
a zero hatch rate, it looks like we won’t hear quail protesting coherently when
they are being picked out for the pot at your next dinner party.
