1 00:00:02,040 --> 00:00:07,080 Speaker 1: Welcome to brain Stuff from How Stuff Works, Hi brain Stuff, 2 00:00:07,160 --> 00:00:10,080 Speaker 1: Lauren vocal Bomb. Here Peru's the egg section of a 3 00:00:10,080 --> 00:00:12,959 Speaker 1: grocery store of Farmer's Market, and you'll notice cartaons of 4 00:00:13,000 --> 00:00:16,840 Speaker 1: eggs separated into white and brown, and sometimes even green 5 00:00:16,920 --> 00:00:19,560 Speaker 1: or blue eggs. But once they arrive scrambled on a 6 00:00:19,600 --> 00:00:21,880 Speaker 1: plate or baked into a cake, it's tough to tell 7 00:00:21,880 --> 00:00:24,959 Speaker 1: the difference. So what is the difference between eggs with 8 00:00:25,000 --> 00:00:28,600 Speaker 1: shells of different colors? This isn't a situation like rice 9 00:00:28,720 --> 00:00:31,560 Speaker 1: or flour. Brown eggs are not more natural, and white 10 00:00:31,560 --> 00:00:34,880 Speaker 1: eggs have not been dcolored with bleach. Both varieties occur 11 00:00:35,000 --> 00:00:39,040 Speaker 1: completely naturally, as do bluish green chicken eggs. But really 12 00:00:39,280 --> 00:00:41,760 Speaker 1: all chicken eggs are the same on the inside. So 13 00:00:41,840 --> 00:00:44,840 Speaker 1: what causes different egg colors among the same type of bird. 14 00:00:45,640 --> 00:00:49,279 Speaker 1: We spoke with Dr Justin Fowler. We cannot make this up, 15 00:00:49,520 --> 00:00:53,400 Speaker 1: Who's a professor at the University of George's Poultry science department. 16 00:00:53,800 --> 00:00:56,920 Speaker 1: He said, the different colors, or the presence of spots 17 00:00:57,000 --> 00:00:59,760 Speaker 1: or speckling, come down to the genetics of the bird. 18 00:01:00,320 --> 00:01:02,800 Speaker 1: Leghorn chickens, which make up most of the commercial egg 19 00:01:02,800 --> 00:01:06,080 Speaker 1: industry in the United States lay white eggs, while Orphington's 20 00:01:06,160 --> 00:01:09,520 Speaker 1: or plymouth rocks will lay brown eggs. The Amerquana breed 21 00:01:09,560 --> 00:01:12,280 Speaker 1: has a pigment that's able to permeate the whole egg 22 00:01:12,360 --> 00:01:14,959 Speaker 1: shell and make blue colored eggs that are colored on 23 00:01:15,000 --> 00:01:18,440 Speaker 1: both the inside and outside of the shell. So there 24 00:01:18,440 --> 00:01:21,160 Speaker 1: you go. I want to know whether a specific chicken 25 00:01:21,200 --> 00:01:23,280 Speaker 1: will pop out a white egg or a colored egg. 26 00:01:23,360 --> 00:01:27,560 Speaker 1: Examine the chicken's earlobe. Surprise, birds have ear lobes more 27 00:01:27,600 --> 00:01:30,399 Speaker 1: often than not. Chickens with white or lighter ear lobes 28 00:01:30,440 --> 00:01:33,520 Speaker 1: tend to have white feathers and thus white eggs, while 29 00:01:33,560 --> 00:01:36,240 Speaker 1: those with colored feathers and ear lobes tend to produce 30 00:01:36,360 --> 00:01:40,399 Speaker 1: colored eggs. Where does this color come from? Though, Here's 31 00:01:40,440 --> 00:01:43,480 Speaker 1: where Understanding how an egg comes to be is important. 32 00:01:43,880 --> 00:01:47,520 Speaker 1: Chicken yolks or ova form in the chickens ovaries. A 33 00:01:47,600 --> 00:01:50,480 Speaker 1: fully formed ovum will leave the ovary and be deposited 34 00:01:50,480 --> 00:01:53,960 Speaker 1: into the oviduct. This part of the chicken's reproductive system 35 00:01:54,000 --> 00:01:57,840 Speaker 1: has five distinct sequential segments which the yolk passes through 36 00:01:57,880 --> 00:01:59,960 Speaker 1: on its way to the outside world. But it's the 37 00:02:00,040 --> 00:02:02,960 Speaker 1: fourth one, the shell gland, that affects the color of 38 00:02:03,000 --> 00:02:06,560 Speaker 1: the egg. This is where the shell forms around the ovum. 39 00:02:06,680 --> 00:02:10,040 Speaker 1: Fowler explained the process. He said, the shell of all 40 00:02:10,120 --> 00:02:13,280 Speaker 1: chicken eggs are made of calcium carbonate, a crystal that's 41 00:02:13,280 --> 00:02:16,160 Speaker 1: white in color. So all eggs are at least at 42 00:02:16,200 --> 00:02:19,240 Speaker 1: the start white. Any that we then see that our 43 00:02:19,280 --> 00:02:21,799 Speaker 1: other colors have had a pigment deposited on them as 44 00:02:21,840 --> 00:02:24,440 Speaker 1: they were moving through the overduct, after the white egg 45 00:02:24,440 --> 00:02:26,920 Speaker 1: shell had been deposited. You can see this if you 46 00:02:26,960 --> 00:02:28,840 Speaker 1: open up a brown egg and look at the inside 47 00:02:28,840 --> 00:02:32,760 Speaker 1: of the shell, it'll be white. Two pigments are responsible 48 00:02:32,760 --> 00:02:35,799 Speaker 1: for the spectrum of chicken egg color. Shades of greens 49 00:02:35,800 --> 00:02:38,160 Speaker 1: and blues are caused by the pigment bill of vert in, 50 00:02:38,360 --> 00:02:42,840 Speaker 1: while protoporphyrin is responsible for reddish brown hues. The same 51 00:02:42,919 --> 00:02:46,280 Speaker 1: egg coloring process holds true for all birds with colorful eggs. 52 00:02:46,560 --> 00:02:50,680 Speaker 1: American robin eggs, for instance, are famously blue. Oh but 53 00:02:50,840 --> 00:02:53,120 Speaker 1: that egg inside an egg story that you might have 54 00:02:53,120 --> 00:02:56,280 Speaker 1: seen going around the internet, that's another thing entirely, and 55 00:02:56,400 --> 00:03:01,000 Speaker 1: involves an egg accidentally reversing its course in the oviduct. Meanwhile, 56 00:03:01,160 --> 00:03:04,239 Speaker 1: we'll leave you with the answer to a practical egg query. 57 00:03:04,680 --> 00:03:07,960 Speaker 1: Should chicken eggs be kept refrigerated or at room temperature. 58 00:03:08,639 --> 00:03:11,640 Speaker 1: It depends on whether you live in a country Australia, Japan, 59 00:03:11,680 --> 00:03:14,600 Speaker 1: and the United States, for instance, that requires eggs produced 60 00:03:14,639 --> 00:03:18,760 Speaker 1: for commercial sale to be washed. This protects against salmonella, 61 00:03:18,960 --> 00:03:22,120 Speaker 1: but also removes a waxy shell coating that naturally defends 62 00:03:22,160 --> 00:03:31,760 Speaker 1: eggs against micro organisms, thereby necessitating refrigeration. Today's episode was 63 00:03:31,800 --> 00:03:34,800 Speaker 1: written by Christopher Hassiotis and produced by Tristan McNeil and 64 00:03:34,880 --> 00:03:37,360 Speaker 1: Tyler Clang. For more on this and lots of other 65 00:03:37,400 --> 00:03:52,320 Speaker 1: foul topics, visit our home planet, how stuff Works dot com.