Tähkämaa was born in Pargas in 1924.[1] He is an agrologist and agricultural advisor by profession.[2] He is a war veteran and participated in World War II against Soviet Red Army.[3] He was a member of the Centre Party and served as its vice chair between 1980 and 1984.[1] He was elected to the Parliament on 23 March 1970 and served there until 21 March 1991.[1]
Tähkämaa was appointed minister of defense on 15 May 1977 to the second cabinet of Kalevi Sorsa, and his tenure ended on 25 May 1979.[1] Next day he was named as the minister of agriculture and forestry and served in the second cabinet of Mauno Koivisto until 18 February 1982.[1] Tähkämaa continued to hold the same post in the third cabinet of Kalevi Sorsa from 19 February 1982 to 5 May 1983.[1]