Cooing Doves Set Muscle Speed Record
The dove: a symbol of peace, innocence, love, and gentleness, right? Its cooing call is a soothing song to nature lovers. Yet hidden in the throat of the dove is one of the fastest-acting muscles in the animal kingdom, report Elemans et al. in the Sept. 9 issue of Nature.1 The cooing song contains a trill that vibrates at 30 Hz, achieved by specialized throat muscles that move the vibrating membrane in and out rapidly:
A dove’s trill cannot be achieved using typical vertebrate muscles, because they do not switch on and off fast enough to control the trill’s brief sound elements (9 ms). The syringeal muscles must also contract aerobically to power cooing sessions that can last for many minutes. These extreme requirements can be met only by aerobic superfast muscles. This muscle type is the fastest known in vertebrates: its twitch half-time is less than 10 ms, which is one to two orders of magnitude faster than that of typical locomotory muscles. (Emphasis added in all quotes.)
Imagine running a sprint with muscles like that. And now, the rest of the story: other songbirds probably outperform the dove:
Birds modulate their songs extremely rapidly, with frequencies exceeding 100 Hz (ref. 2). Although the intrinsic nonlinear properties of the syrinx add complexity to the level of motor control, only muscle control can explain the fast but gradual modulations that underlie the extraordinary intraspecific variability and flexibility of phonation. The stereotyped coos of doves are considered to be simple vocalizations among birds, but even doves use superfast muscles to control their song. Given their added vocal complexity, songbirds have probably evolved muscles that outperform the syringeal muscles of doves. Superfast muscle can no longer be considered a rare adaptation, found for example in the highly derived acoustic organs of the toadfish and rattlesnake. We suspect that superfast vocal muscles are widespread among birds.
A meadowlark will never sound the same again. Incidentally, another recent paper in Current Biology2 found that parrots have tongues able to modulate sounds much like humans do. That’s one reason they can talk. See also “Parrots speak in tongues” on Nature Science Update. The lead researcher commented, “parrot communication may be more complex than we thought.”
1Elemans et al., “Bird song: Superfast muscles control dove’s trill,” Nature 431, 146 (09 September 2004); doi:10.1038/431146a.
2Beckers et al., “Vocal-Tract Filtering by Lingual Articulation in a Parrot,” Current Biology Volume 14, Issue 17, 7 September 2004, Pages 1592-1597, doi:10.1016/j.cub.2004.08.057.
The variety of sounds birds can make is remarkable.. Some calls, like the dove’s, are soothing and sweet; others, like those of the crow or scrub jay, are raucous and irritating. How their skill is passed from parent to chick over hundreds of generations is also amazing. Isn’t it sweet to know that the birds are out there evolving better and faster muscles, figuring out all the developmental pathways and modulations, understanding nonlinear dynamics, devising and meeting extreme requirements and gearing all the molecular machines, genetic programs and control mechanisms to transform seeds and worms into music? Evolution is such an amazing goddess.