Taking　highly　cited　scientists　in　the　field　of　Molecular　Biology　&　Genetics　and　Physics　as　a　case　study,　and　with　the　method　of　scientometrics,　this　paper　studies　the　age　distribution　at　the　time　of　publication　of　these　scientists　(called　the　publication　age　distribution),　with　the　conclusion　that　these　scientists　publish　most　of　their　articles　mainly　between　the　age　of　40　and　55　(called　middle　age),　showing　the　characteristic　of　cubic　polynomial　model.　In　addition,　a　further　study　on　the　publication　age　distribution　of　older　highly　cited　scientists　was　also　made　in　this　paper.　©2009　IEEE.