An ancient finding

For 12,000 years they lay cradling one another. Their embrace shows that even at the dawn of civilization, we were not alone. Surely the puppy had a name – one that was called out, sometimes affectionately, sometimes sternly by the person whose ancient finger bones were found wrapped around it. Today such sounds are familiar. Back then they heralded the beginning of a partnership that would come to define both species.

Unearthed within a tomb在以色列北部的Ain Mallaha的史前定居点中，这些遗骸属于Natufian文化。他们的定居点提供了人们从猎人的聚集到以驯养动植物为中心的生活方式的证据。

看来狗是第一个进入褶皱的物种。遗传证据表明，在11,000-16，000年前的某个时候开始驯化狗。These bones provide physical evidence from the early stages of this special relationship between human and dog.

The genetics of dog domestication

Before dogs could enter our homes they had to become tame. Yet there is much about the biology behind this transformation that we still don’t know.

Before dogs could enter our homes they had to become tame. Yet there is much about the biology behind this transformation that we still don’t know. To better understand why dogs bound up where wolves fear to tread we turned to the largest publicly available database of dog and wolf genomes.

从这个数据库中称为狗, we compared the genomes of 69 dogs and 7 wolves. The animals were collected from several different locations around the globe.

我们确定了狗和狼高度分化的单核苷酸变体。

Among these we found 2,112 single nucleotide positions in the genome where dogs and wolves completely differ. In other words, if you looked at any one of these sites, you could be sure whether the animal it came from was a dog or a wolf.

We suspected that some of these genetic differences underlie the physical and behavioral changes that occurred during dog domestication. To identify these functional changes we narrowed down our search by only considering the genetic changes that were predicted to change either the protein structure or amount of each gene that is produced.

What did we find?

We identified 848 genes with potentially functional genetic changes that differentiated the majority of dogs and wolves analyzed. To see what this might tell us about dog domestication we tested whether any specific biological pathways had more genes with high frequency genetic differences between dogs and wolves than you would expect by chance.

We found six biological pathways with a significant enrichment of genes with potentially functional differences between dogs and wolves.

We found six biological pathways with a significant enrichment of genes with potentially functional differences between dogs and wolves. The strongest signal was in the adrenaline and noradrenaline biosynthesis pathway.

Adrenaline is a hormone with an important role in the fight-or-flight response. Therefore, we hypothesize that some of the genetic changes in this pathway may underlie the less fearful and aggressive behavior of dogs towards humans compared to wolves.

我们还检测到多巴胺信号通路中基因变化的富集。多巴胺是一种因参与情感处理和奖励行为而闻名的神经递质。我们怀疑其中一些变化在狗驯化过程中也很重要

这是什么意思？

有趣的是，这些基因中有几个包含以前建议与狗品种之间或狗之间的行为差​​异相关的其他变体（例如SLC6A3和MAOB)。这表明这些基因在最初的驯化过程和随后的繁殖形成期间都可能很重要。

These results highlight several genes with changes that may have been involved in the process of dog domestication. Future work will be needed to reveal exactly what effects, if any, these changes have. Furthermore, ancient DNA from dogs and wolves may tell us exactly when and where these changes occurred in the history of dog domestication.