By Walter Scheidel of Stanford University
"The intention to marry one's own former slave justified her manumission before age 30 (the minimum agelimit set by the lex Aelia Sentia); the fact that a slave was the owner's biological child (filius/filia naturalis) activated the same exemption (Gai. Inst. 1.19). And indeed, in some inscriptions the owner of a slave is also the father (Herrmann-Otto 1994: 42-6, 88-90). Filii naturales of this kind are frequently referred to in Roman law: blood ties between owner and slave become a factor in legal discussions of manumission, damage assessment, and inheritance (Rawson 1989: 23-9). The legal anomaly that a slave woman's children were not included among her fruits (unlike in the case of livestock) made it easier for a putative owner/father to retain a child even if the mother was sold (Watson 1987: 103-4). According to Ulpian, one might happen to inherit an estate comprising one's own biological father, mother or brothers (Dig. 30.71.3). Such heirs must have have been the children of testators by their slave women. In his study of Roman wills, Champlin 1991: 137 speculates that slaves instituted as heirs 'may have had a sexual liaison with the testator' or 'may have been an illegitimate child of the testator'. However, even though slaves and ex-slaves could be made heirs (Iavol. Dig. 28.2.11), this often involved adoption (Herrmann-Otto 1994: 85-6 n.179). Slaveowners had no legal obligations to children they fathered with their own slaves. At the same time, they were free to choose to acknowledge, manumit, institute as heir, and adopt any of these children. In this way, Roman slaveowners retained the greatest possible degree of control over the allocation of their material resources: while they were unconstrained in disseminating their genes amongst their slaves, it was also left to them to decide whether or to what extent to match gene flow with the flow of paternal investment: in this regard, their options ranged from the sale of such offspring on one end of the scale to adoption on the other. In short, the Roman slave system optimised 'marginal reproductive success'. Syme 1960/79: 511 notes the 'singular dearth of evidence about aristocratic bastards', which he attributes to a pervasive code of silence. This silence will best be taken as powerful testimony to the masterful efficiency of the Roman elite in separating acknowledged from marginal progeny, and in regulating paternal investment accordingly."