我们是很在意发量的，普通的成年人头皮毛囊大概有 8 万–15 万个，可是全身绝大多数体毛退化了。早期的鸟类学家手工逐根数毛，发现了鸟类羽毛的秘密。曾经有一个规律，体型越大，单位体重羽毛越少。小天鹅站了出来打破了规律。以前全认为帝企鹅羽毛密度最高，新研究发现它正羽密度其实一般，可是算上基部副羽、绒羽，总羽量登顶鸟类冠军。潜水的白喉河乌全身是毛，红喉北蜂鸟的毛量为了飞行而妥协。

告别焦虑吧，朋友。毛发多少这些全是大自然安排的。

好“鹅”一身毛

“划水”的鸟 白喉河乌

会飞，毛少.....

参考文献

Ammann, G. A. (1937). Number of contour feathers of Cygnus and Xanthocephalus. The Auk, 54(2), 201–202.

Wetmore, A. (1936). The number of contour feathers in Passeriformes and related birds. The Auk, 53(2), 159–169.

Hutt, F. B., & Ball, L. (1938). Number of feathers and body size in passerine birds. The Auk, 55(4), 651–657.

Williams, C. L., Hagelin, J. C., & Kooyman, G. L. (2015). Hidden keys to survival: The type, density, pattern and functional role of emperor penguin body feathers. Proceedings of the Royal Society B: Biological Sciences, 282(1817), 20152033.

Kiat, Y., & O'Connor, J. K. (2024). Functional constraints on the number and shape of flight feathers. Proceedings of the National Academy of Sciences, 121(8), e2306639121.

Ng, C. S., & Li, W.-H. (2018). Genetic and molecular basis of feather diversity in birds. Genome Biology and Evolution, 10(10), 2572–2586.

Davenport, J., O'Halloran, J., Hannah, F., McLaughlin, O., & Smiddy, P. (2009). Comparison of plumages of white-throated dipper Cinclus cinclus and blackbird Turdus merula. Waterbirds, 32(1), 169–178.

Davenport, J., Hughes, R. N., Shorten, M., & Larsen, P. S. (2011). Drag reduction by air release promotes fast ascent in jumping emperor penguins — a novel hypothesis. Marine Ecology Progress Series, 430, 171–182.

Paus, R., & Cotsarelis, G. (1999). The biology of hair follicles. New England Journal of Medicine, 341(7), 491–497.

Buffoli, B., Rinaldi, F., Labanca, M., Sorbellini, E., Trink, A., Guanziroli, E., Rezzani, R., & Rodella, L. F. (2014). The human hair: From anatomy to physiology. International Journal of Dermatology, 53(3), 331–341.

Pagel, M., & Bodmer, W. (2003). A naked ape would have fewer parasites. Proceedings of the Royal Society B: Biological Sciences, 270(Suppl. 1), S117–S119.

Prum, R. O., & Brush, A. H. (2002). The evolutionary origin and diversification of feathers. The Quarterly Review of Biology, 77(1), 3–55.

Chen, C.-F., Foley, J., Tang, P.-C., Li, A., Jiang, T.-X., Wu, P., Widelitz, R. B., & Chuong, C.-M. (2015). Development, regeneration, and evolution of feathers. Annual Review of Animal Biosciences, 3, 169–199.

Ho, W. K. W., Freem, L., Zhao, D., Painter, K. J., Woolley, T. E., Gaffney, E. A., McGrew, M. J., Tzika, A., Milinkovitch, M. C., Schneider, P., Drul, A., et al. (2019). Feather arrays are patterned by interacting signalling and cell density waves. PLoS Biology, 17(1), e3000132.

Jung, H.-S., Francis-West, P. H., Widelitz, R. B., Jiang, T.-X., Ting-Berreth, S., Tickle, C., Wolpert, L., & Chuong, C.-M. (1998). Local inhibitory action of BMPs and their relationships with activators in feather formation: Implications for periodic patterning. Developmental Biology, 196(1), 11–23.

Harris, M. P., Williamson, S., Fallon, J. F., Meinhardt, H., & Prum, R. O. (2005). Molecular evidence for an activator-inhibitor mechanism in development of embryonic feather branching. Proceedings of the National Academy of Sciences, 102(33), 11734–11739.

Dawson, C., Vincent, J. F. V., Jeronimidis, G., Rice, G., & Forshaw, P. (1999). Heat transfer through penguin feathers. Journal of Theoretical Biology, 199(3), 291–295.

Du, N., Fan, J., Wu, H., Chen, S., & Liu, Y. (2007). An improved model of heat transfer through penguin feathers and down. Journal of Theoretical Biology, 248(4), 727–735.

Rijke, A. M., & Jesser, W. A. (2010). The feather structure of dippers: Water repellency and resistance to water penetration. The Wilson Journal of Ornithology, 122(4), 727–733.

Mallo, M. (2021). Of necks, trunks and tails: Axial skeletal diversity among vertebrates. Diversity, 13(7), 289.

BGM

Wind In Your Hair - Single azayaka

Hair up - Justin Timberlake, Gwen Stefani & Ron Funches