Picture Credits

Providers of pictures:
 

Shutterstock:

Sven Hope, Kesu, Igor Normann, Oleg Kozlov, Graham Taylor, Ragnarock, Alexander Ishchenko, Pan Xunbin, Michael Pettigrew.
 

Fotolia:

Spencer, Gabriella88, Andre, mtsyri, mica, ExQuisine, blende40, Heike Rau, yamix, H.D. Volz, Benshot, reises

Dr. Gary Alpert/Harvard University & Piotr Naskrecki