Original sentence: "  In spite of sharing primitive external features, the Konik and Heck horses have markedly different conformation with differently-proportioned body measurements, most likely linked to environmental factors.A number of genotypes have been identified within European wild horses from the Pleistocene and Holocene; their color genes including those creating bay, black and leopard spotting are known to be present in the wild horse population in Europe.By the 1960s they produced the Heck horse.However, this does not prevent some modern breeders from marketing horses with these features as a "Tarpan.In the early 1930s, Berlin Zoo Director Lutz Heck and Heinz Heck of the Munich Zoo began a program crossbreeding Koniks with Przewalski horses, Gotland Ponies, and Icelandic horses.In the mid-1960s, Harry Hegard started a similar program in the United States using Mustangs and local working ranch horses that has resulted in the Hegardt or Stroebel's Horse.Three attempts have been made to use selective breeding to create a type of horse that resembles the Tarpan phenotype
Edited sentence: A number of genotypes have been identified within European wild horses from the Pleistocene and Holocene; the color genes including those creating bay, black and leopard spotting are known to be present in the wild horse population in Europe.In spite of sharing primitive external features, the Konik and Heck horses have markedly different conformation with differently-proportioned body measurements.In the early 1930s, Berlin Zoo Director Lutz Heck and Heinz Heck of the Munich Zoo began a program that by the 1960s produced the Heck horse, which is a crossbred of Koniks with Przewalski horses, Gotland Ponies, and Icelandic horses.In the mid-1960s Harry Hegard started a similar program in the United States using Mustangs and local working ranch horses that has resulted in the Hegardt or Stroebel's Horse.Some connect this to environmental factors, although Heck horse and Konik horse have a considerably different breed history.Three attempts have been made to breed a type of horse that resembles the Tarpan phenotype