一项国际团队以高灵敏度基因组方法分析 2,693 份犬与狼的基因组，发现 64.1% 的纯种犬带有狼 DNA 片段；另一项针对全球村犬的研究也在 280 只幼犬中全部检出狼的遗传痕迹。这颠覆了「犬狼杂交极罕见、现代犬几乎不含狼基因」的既有看法。

研究推估狼→犬的基因流平均发生在约 1,000 代之前（约 3,000 年前），而犬→狼的基因流则更近，集中在 19 世纪初，可能与都市化带来的流浪犬增加相关。虽然在全基因组层面犬与狼可清楚区分，但对 1,582 个基因逐一建树后，没有任何一个基因支持「犬为单系群」，并且在粒线体与 Y 染色体树上呈现多轮次、双向的基因交流讯号。

狼基因与体型与性情呈趋势关联：大型犬整体更常见狼祖源；部分守卫犬仍有 0.5–1.2% 狼祖源，而吉娃娃也约有 0.2%。刻意培育的狼犬品种可达 23–40%，典型犬种中也有约 4.7–5.7%、2.7%、3.7% 等差异。功能上，村犬富集区域唯一显著类别是嗅觉传导，可能帮助在艰困环境觅食；都市流浪犬 5 个月存活率低于 37%，甚至可低至 16%。另如藏獒的 EPAS1 变异源自藏狼，研究样本 10 只皆为同型合子，显示狼基因可作为适应工具。

Using sensitive genome-wide analyses of 2,693 dog-and-wolf genomes, researchers detected wolf DNA fragments in 64.1% of purebred dogs. A separate global study of free-roaming “village dogs” found wolf traces in all 280 pups examined. Together, these results challenge the long-held view that post-domestication wolf–dog interbreeding is extremely rare and that modern dogs should contain little to no wolf ancestry.

Estimated introgression is asymmetric in time: wolf-to-dog gene flow averages about 1,000 generations ago (roughly 3,000 years), while dog-to-wolf gene flow is far more recent, clustering around the early 19th century and plausibly linked to urbanization and rising stray-dog populations. Although dogs and wolves separate at whole-genome scale, gene-by-gene phylogenies across 1,582 genes found no single gene supporting strict dog monophyly, and mtDNA/Y-chromosome trees point to repeated, complex exchanges.

Wolf ancestry correlates with traits and survival pressures. Larger and some working breeds tend to carry more wolf ancestry; livestock guardian breeds show about 0.5–1.2%, while even Chihuahuas average ~0.2%. Deliberately bred wolfdogs reach ~23–40%, and some standard breeds show notable levels (e.g., ~4.7–5.7%, 2.7%, 3.7%). In village dogs, wolf-enriched regions significantly implicate olfactory transduction, relevant where 5‑month survival in urban strays is <37% and sometimes ~16%. Tibetan mastiffs also carry a Tibetan-wolf–derived EPAS1 variant; all 10 sampled were homozygous, consistent with rapid high-altitude adaptation.